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193 Cards in this Set
- Front
- Back
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GSSP
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Acronym for Global Standard boundary Section and Point
- An internationally ratified point in strata marking the boundary between two time-rock units |
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How does vertical stacking of strata provide clues to depositional environments?
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1. Suites of closely associated rocks are needed in order to identify an ancient environment
2. The constituents of the strata, as well as fossils, weather markers and uplifting can point to a depositional environment |
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Walther's Law
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Lithologies that comfortable overlie one another must have accumulated in adjacent depositional environments.
- Exceptions occur where there are erosional breaks - This law allows for transformations from the vertical data to a horizontal set and is often used wen a vertical sequence of facies has been identified and characterized |
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What sedimentary features result from deposition in particular non-marine environments?
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1. Some types of ancient soils reflect the climatic conditions under which they formed
2. Lake deposits are chracterized by thin horizontal layers, few burrows, and an absence of marine fossils 3. Glaciers often leave diagnostic striations on rock faces, poorly sorted gravel material, and associated glaciolacustrine deposits |
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What are the distinctive features of marginal marine + continental shelf deposits?
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Where a river meets a lake or ocean, it forms a delta
- Deltaic depositino typically produces upward coarsening sequence of materials 2. Coral reefs border many tropical shorelines - a typical reef stands above the surrounding seafloor - Coral reefs form many parts of carbonate platforms - Coral reefs turn in to limestone |
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What are the characteristics of deep sea sediments?
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1. Beyond the edge of the continental shelf, turbidity currents intermittently sweep own continental slopes out to the continental rise + abyssal plain (forming turbidites)
2. Very far from the shelf, only fine grained sediments are accumulated |
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Time units of stratigraphy
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1. Eras
2. Periods 3. Epochs 4. Ages |
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What is a rock facies?
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A set of characteristic strata that formed in a particular event
- A formation may be a single, or two adjacent facies |
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What rocks and fossils in Africa + S. America suggest that those two continents were connected to each other as parts of Gondwanaland in late Paleozoic?
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1. Many kinds of non-marine organisms (Glossopteris:fern, mesosaurus: reptile)
2. Rock sequence in Africa was identical to Brazil 3. Matching mountain belts |
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How does paleomagnetism demonstrate that the continents have been moving over time?
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1. Magnetism frozen into ancient rocks is not aligned with the Earth's present magnetic field
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How does continental rifting begin, and what environments of deposition does it produce?
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1. Fracturing of continents often begins with doming of crust in the middle
- each dome fractures and becomes a three-arm system and rifting begins |
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Ophiolite
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The remnant of a sea floor
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How did the Andes form?
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The Andes rose up as a result of subduction of an oceanic plate along the west coast of S. America
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Pyrenees
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Collision of Iberia + Eurasia
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What fundamental principles guide geologists as they reconstruct Earth's history?
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Actualism
- fundamental to natural science, asserts that the laws of science do not vary over the course of time |
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What are the basic kinda of rock and how are they interrelated?
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1. Sedimentary
2. Igneous 3. Metamorphic |
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How do geologists unravel the age of rocks?
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1. Principles of horizontality
2. Principle of superposition 3. Original Lateral Continuity 4. Chemical dating |
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Eras + Times of the Phanerozoic
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1. Paleozoic (524-251 mya)
2. Mesozoic (251-65.5 mya) 3. Cenozoic (65.5 mya- ) |
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Periods of the Paleozoic
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1. Cambrian
2. Ordovician 3. Silurian 4. Devonian 5. Carboniferous 6. Permian |
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Periods of the Mesozoic
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1. Triassic
2. Jurassic 3. Cretaceous |
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Periods of the Cenozoic
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1. Paleogene
2. Neogene 3. Quaternary |
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Cambrian
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(542-488.3 mya)
Cambrian explosion (lifey sea, barren land) |
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Ordovician
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(488.3-443.7 mya)
Gondwana Taconic Mountains Mass extinction of planktonic forms Trilobites/brachiopods/cephalopods/ crinoids |
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Silurian
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(443.7-416 mya)
Jawed + Bony fish Stable + warm vascular plants on land Patchy reefal systems ** These are the rocks from the field trip |
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Devonian
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(416-359 mya)
Adaptive Radiation of terrestrial life + fish diversity warm (high seas) THE AGE OF FISH terrestrial arthropods |
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Carboniferous
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359.2-299 mya
Terrestrial life Amphibians Large Arthropoda Pangea bivalves important evolution of egg |
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Permian
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299-251 mya
Trilobites extinct Pleycosaurs + amphibians Cynodonts + synapsids! |
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Triassic
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251-199.6 mya
2 Major extinctions (start + end) Permian-Triassic extinction event (252mya) - 96% marine life, 70% terrestrial - 'disaster taxa': Taxa that colonize the land after a major disaster (primary colonizers) |
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Jurassic
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199.6-145.5 mya
AGE OF REPTILES Pangea split into Laurasia (North) and Gondwana (South) FIRST BIRDS |
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Cretaceous
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145.5-65.5 mya
warm New mammals + birds + angiosperms Ended with Cretaceous-Paleogene extinction (K-Pg boundary) Gondwana breaks up (S. America/Antarctica/ Australia/ Africa) Insects diversified |
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Paleogene
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65.5-23.03 mya
Mammals No more dinos Rocks = "Paleogene System" SO MANY MAMMALS |
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Neogene
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23.03-2.588 mya
Mammas + birds = roughly modern EARLY HOMINIDS modern continents Grasses + prairies diversified Hominids moved into Eurasia |
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Quaternary
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2.588 mya- now
Short glaciations in N. Hemisphere Pleistocene, Holocene, (Anthropocene?) Recognizable humans |
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P(COSDCP)
M(JTC) C(PNQ) |
you know it
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Biostratigraphy
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- Fossil record in the rocks
Fossil records can help correlate rocks through morphologies |
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Lithostratigraphy
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- Lithostratigraphic units are time-transgressive
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Lithification
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Involves compaction; as sediment is deposited, the weight of the overlying sediment compacts an lithifies older layers
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Cementation
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Involves the precipitation of minerals out of water, which glues grains together and further reduces pore spaces
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Wacke/ (Greywacke)
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* CONTAINS MUD
- Laid down by turbidity currents - Contains poorly sorted levels of gravels, muds and sands - Grey |
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Arenite
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Sedimentary clastic rock
No Mud |
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What is a Basin?
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- Any geographical feature (container) exhibiting subsidence (sinking) and infilling by sedimentation
- As more sediment is deposited, the weight of it may cause the basin to subside further Example: Mississippi Delta - Continues to have sediment deposited in it, and continues to subside (resulting in a basin km in thickness) |
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Plate Tectonics Theory
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Scientific theory that the lithosphere is cracked and composed of pieces that interact with each other as they float on the asthenosphere
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Plate Motion
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Plates move 1-7cm a year, causing plates to converge/ diverge/ slide
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Wilson Cycle
Formation of a basin and then the process of its destruction |
1. Stable craton
2. Early rifting 3. Full ocean basin 4. Subduction zone 5. Closing ocean basin 6. Orogeny collision |
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Isostatic Changes
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Less dense crust will tend to ride topographically higher than areas of denser material
(Crust responds to addition of sediment/water/ice) |
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Eperic Basins
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Semi-circular downwards in continental interiors
Causes: Underlying rifts, large-scale fault blocks, cooling after intrusion, mantle cold spots, phase changes Example: Caspian sea |
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Why/ how are carbonate sediments "born"?
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- Carbonate sediments are created through biological growth and not made like their clastic counterparts, by weathering of parent material
- Made from the biological precipitation of calcium out of seawater |
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Allochems (Bioclasts)
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Silt, sand, and gravel sized carbonate particles that form the framework of rock:
- Mollusce/ Brachiopods/ Echiniods/ Crinoids |
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Insitu Bioclasts
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Corals, algae that have not been transported (in situ), and sediment has infilled around the skeletons
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Oolithic Sands
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Oolite grains can be so abundant that they form oolite sands
Example: Most Carribean islands are oolithic sands |
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Peloids
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Carbonate fecal pellets; no internal layering, form in quiet environments
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Folk Classification
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Allochems vs. Orthochems
** Learn to draw this |
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Dunham Classification
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Based on the concept of the grain
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Evaporites
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Gypsum (calcium sulfate dihydrate)
Anhydrite (calcium sulfate) Halite (often called rock salt) Found in bed form Sea water needed to form |
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Chert
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Nodules of chert might be present in limestones
- Chert is from siliceous micro-organisms-diatoms, radiolarans and some sponges * The siliceous skeletons accumulate in beds, which dissolve and re-precipitate as crypto-crystalline or microcrystalline chert |
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Primary sediment structures are the result of sediment movement by:
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- Water (unidirectional-current/oscillatory-tidal)
- Ice - Gravity - Wind - Biological activity |
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Particle Entrainment
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Critical threshold for grain movement depends on:
- Boundary shear stress - Fluid viscosity - Particle size/ shape/ density |
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What type of rock has a mud matrix:
- wacke - mudstone - lithic wacke - wackestone - ALL |
ALL
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A crinoid has a segmented:
-root -stem -shell -valves -none |
stem
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The Paleozoic ended with the:
-Triassic - Cambrian - Ordovician -Carboniferous |
none (the answer is Permian)
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What came after the Ordovician?
- Silurian - Devonian -Cambrain -Permain -Jurassic |
Silurian
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Corals live in:
- Tropical ocean - The photic zone - Clear sediment free water - Benthic environments All |
ALL
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Planktic means
-A sinker - a swimmer - bottom dwelling - burrower - none |
Swim (float)
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Wave Base
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Water depth at which there is no wave movement
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Fair-weather wave base
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depth beneath the average daily waves
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Storm Wave Base
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depth beneath storm driven waters
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Why do thin laminations often occur in hypersaline rocks?
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Very few organisms can live in hypersaline conditions, Therefore there is no bioturbation to churn the rock into a massive body
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Normal grading
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Finer moving upward
- most common |
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Reverse grading
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Coarser grains moving to finer grains
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Dropstones
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Indicative of icebergs, slow water environment
Dropped vertically through water column and sediment is placed on top |
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Trace Fossils
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Evidence of biological activity, without the organism
- Tracks, trails, burrows |
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What are the two mineral groups which contribute most to the rock record?
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Silicates
Carbonates |
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Silicate Minerals
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Dominant group in igneous, sedimentary, and metamorphic rocks
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Carbonate Minerals
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- Containing calcium, magnesium, iron, or other ions adhered to a carbonate ion
- Important in sedimentary rocks |
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What are fossils?
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Fossils incluse hard parts of organisms, which have sometimes been chemically altered, as well as the molds of those structures
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Anhydrite
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Evaporite
- Calcium sulfate - Colourless to pale blue/violet - Fibrous parallel veins |
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Intraclasts
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Pieces of previously formed limestone or lithified sediment that has been eroded from the sea bed or comes from older limestone outcrops in the area
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Limestone types + environment:
Basin |
Mudstone + chalks
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Limestone types + environment:
Foreslope |
Grainstone
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Limestone types + environment
Large waves |
Boundstone
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Limestone types + environment
Carbonate shoals (large waves, tidal currents) |
Grainstone/ Packestone
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Limestone types + environment
Carbonate platform (clear calm water) |
Mudstone/ wackestone
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Allochemical Rocks
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Allochems: transported some ways, includes
- fossils - ooids - pellets - intraclasts |
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Orthochemical Rocks
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Orthochemical: grown biologically
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Polymorphic species
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Look similar but cannot interbreed (convergent evolution)
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How to tell a carbonate rock from a siliceous rock:
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Use some HCL
Carbonate will fizz siliceous will not EXAMPLE: Dolostone (limestone) will fizz, and chert (silicified limestone) will not |
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GOBE
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Great Ordovician Biodiversity Event
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Jolly Cut Formations
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Silurian
Lockport Rochester Irondequoit Reynales Thorold Grimsby |
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Transgression
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Rise of sea level and submergence of the continent under seawater
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Regression
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A drop of sea level and withdrawal of water from the land
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Aeolian Deposition
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Distinct cross bedding
- mudcracks + root casts are often preserved in "inter dune" areas Facies Dunes: High angle cross-bedding from unidirectional flow - fine to medium sand, well sorted Facies Interdune: Silty, mudcracks, root casts, may be laminated |
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Playa/ Evaporitic Lakes
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Typically occur in arid settings
- Episodal rainfall brings water into low-lying areas - May be evaporitic/ saline Facies: fine grained muds and possibly evaporites, limited bioturbation/ fossils |
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Glacial Landscapes
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Very sandy
Poorly Sorted Coarse grained Well rounded Facies: Till- diamicts generally poorly to well sorted sandstones, conglomerates, with rounded clasts and both framework or matrix supported - Cross bedding to massive graded sediments may be common Facies: Glacio-lacustrine - Mostly mud sized sediment, often laminated, dropstones apparent |
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Alluvial Fans
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Massice to graded sediments ranging from coarse gravels to boulders to finer sands and muds
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Lacustrine
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Facies: Mostly shales + mudstones, but also limestones.
- may be laminated or massive, bioturbated Few fossils |
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Alluvial Facies
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Meandering- muds + sands, poorly sorted, planar beds, asymmetric cross stratification, may be graded, cut and fill stratigraphy common
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Factors affecting marine environments
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- Waves
- Tides - Turbidity Currents - Thermohaline circulation |
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Turbidity Currents
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Density currents- suspension of sediments which are denser than the surrounding water flow downslope eroding + transporting sediment
- Caused by storms, earthquakes, failure of sediment - Most important on slope/ rise |
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Thermohaline Circulation
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Density differences in surface water due to temperature or salinity create vertical circulation of water masses in oceans
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Paleontology
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Paleontology is founded upon the collection, identification, and environmental interpretation of the remains or traces of ancient organisms
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Paleo-environmental Analysis
(3 steps) |
1. Document the species in the fossil assemblage
2. Compare the species in the assemblage with known paleoecological data to determine environment 3. Document taphonomic character to understand sedimentary processes |
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Taxonomic Hierarchy
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Kingdom
Phylum Class Order Family Genus Species |
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Endoskeleton
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Internal frame for tissue and muscles
- Calcium phosphate |
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Exoskeleton
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External covering for protection and frame to told tissue and muscles, may be segmented
- chitin/ calcium carbonate |
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Accretion
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Skeletons grow by accretion- adding new material onto the surfaces or edges of previously grown skeletal elements
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Addition
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Some organisms have compound skeletons that consist of differnt elements such as plates/ spines
- Sea urchins |
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Life Modes:
Benthic Planktic Nektic Neritic Pelagic Infaunal Epifaunal |
Benthic: Live on the sea floor (on or in sediment)
Planktic: Drift passively (float/ drift passively in and around water column Nektic: active swimmers Neritic: inhabit shallow waters near land Pelagic: inhabit surface/ middle depths of ocean Infaunal: Living in the sediment Epifaunal: Living on the sediment |
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Name some limiting factors that control the proliferation of organisms in a marine setting:
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Salinity
Temperature Oxygen availaibility Nutrient availability Water energy |
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Stenohaline
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Taxa that can live in a narrow range of salinities
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Euryhaline
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Taxa that can live in a wide range of salinities
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Taphonomy
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Process of fossilization
- Har bodied organisms are much more likely to survive fossilization = FOSSIL BIAS |
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Evidence of fossil transport
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- Fragmentation
- Edge rounding - Degree of articulation of skeleton - Concentration of shells - Orientation of shells (insitu/ imbricated) |
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Fossilization: Replacement
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Silicification, pyritization
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Fossilization: Recrystalization
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Aragonite to calcite
Calcite to dolomite |
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Fossilization: Permineralization
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Addition of minerals to pore spaces
- common in porous bone/ wood |
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Fossilization: Phosphatization
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Thin organic shelled organisms may be replaced or overgrown by a sheet of phosphate
- occurs in anoxic environments |
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Fossilization: Concretion
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Usually carbonate masses forming around fossil shortly after burial
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What types of corals were abundant in the Paleozoic?
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Rugose + Tablulate corals
- Sessile, benthic, lived in photic zone - extinct by P-T boundary - Radial/ bilateral symmetry |
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Brachiopods
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Paleozoic
Look like clams Benthic marine Bilateral top symmetry |
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Gastropods
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Trocospiral/ planispiral shells
Earliest were from Cambrian Benthic bottom feeder * Distinction between cephalopods: Gastropoda do not have a chambered shell |
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Bivalves
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Still around today
- Showed up in Ordovician - infaunal/ epifaunal - Sessile |
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Cephalopods
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Important in mesozoic (index fossils)
- Chambered shell - Nektic |
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Sponges
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Benthic sessile filter feeders that utilize cells to pump water through canal systems
Needle like spicules often preserved in rocks (chert nodules) |
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Graptolites
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Cambrian to Pennsylvanian
-Planktic or benthic - Index fossils - Typically found within black shales |
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Bryozoans
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Mossy texture
- Paleozoic to recent - Benthic marine/ brackish - Branching (low energy area) - Encrusting (high energy areas) |
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Trilobites
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Dominant from Cambrian to Upper Permian (Great index fossil for Paleozoic)
-Marine arthropods - chitinous exoskeleton - Generally mobile benthic epifaunal detritus feeders - Bilateral symmetry |
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Invertebrate Fossil Trends with Environment: Freshwater
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Moderate to low diversity
- Mostly benthic stenohaline |
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Invertebrate Fossil Trends with Environment: Brackish coastal
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Low to moderate diversity, mostly benthic brackish euryhaline taxa, including a mixture of marine + freshwater
- Form mostly shell beds |
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Invertebrate Fossil Trends with Environment: Marine Shelf
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High diversity, abundance, mostly benthic + nektic marine stenohaline
- Form mostly shell beds |
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Invertebrate Fossil Trends with Environment: Marine coral reef
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High diversity and abundance of shelly material
Shell beds, but also corals and shells in growth position |
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Invertebrate Fossil Trends with Environment: Deep marine
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Mostly microfossils- plankton, but also nektic + benthic
- Accumulation of most fossil debris |
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On any coastline, reconstructing sea level from the stratigraphic record is a function of:
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1. Water volume
2. Changing shape of the basin that holds the water 3. Stability of the sides of the basin 4. Distribution of the water in the basin |
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Factors leading to global sea level change
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1. Quantity of water
- Glacio-Eustatic, Tectono-Eustatic 2. Sedimentation Rates |
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Factors leading to Local/ regional sea level change
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1. Isostatic variations
2. Tectonic Variations 3. Sediment compaction 4. Water surface elevation changes |
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Glacial Eustacy
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- Largest global factor of sea-level change
- Involves differences in ocean level of ~ 100 m over the last interglacial period |
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Tectono Eustacy
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Long term sea level changes affects the shape + extent of the oceanic basin
1. Plate tectonics: convergence (subduction of crustal plates) 2. Variation in ocean spreading rates, continental breakup |
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Sedimentation rate (factors affecting sea level)
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The volume of ocean basins is controlled by sedimentation
- Filling of ocean basins with continental sediments is a relatively slow way of reducing ocean basin capacity |
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Isostacy:
Sedimentary isostacy Hydroistostacy Glacioistostacy |
Isostacy: Depression/ rebound of crust
Crust will subside under an immense weight of water/ ice/ sediment On the other hand, land will rise when that sediment/ ice/ water is taken off ** This was an important mechanism during interglacial periods, as the rapid melting of ice results in a rebound of crust |
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Prokaryote
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No distinct membrane bound nucleus or membrane-bound organelles
- DNA is not organized into chromozomes |
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What type of life dominated the Archean?
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Life was dominated by prokaryotes
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Important steps by Proterozoic Life Forms
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Heterotrphy is how eukaryotic cells formed (symbiosis)
- Evolution of skeletons for protection |
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Why is heterotrophy so important for the evolution of life?
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Heterotrophy gained its importance as the probably means by which the eukaryotic cell initially evolved (through the symbiotic association of predator + undigested prey)
- Later, heterotrophy became a major driver in the evolution of skeletons + behavioural strategies in animals |
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Stromatolites
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Sheet like mats and domes buildups of marine microbes- colonies of photosynthesizing cyanobacteria
- Only found in very "harsh" environments today (no gastropods to consume them) |
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Early Eukaryotes
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Eukaryotes: cell type with a true nucleus
All eukaryotic cells contain mitochondria -Inside eukaryotic cells are distinct masses presumed to be remains of cell nuclei or other organelles The oldest known multicellular eukaryotes are algae resembling modern seaweed |
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What is the significance of the Ediacaran (in the formation of life?)
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First multicellular organisms
- Until the Ediacaran, most organisms were microscopic No shells/ skeletons |
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The Ediacaran-Cambrian Transition
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Stage 1: Trace Fossils
- Complex trace fossils indicating advanced behaviour - Prior to Cambrian, trace fossils are simple Stage 2: Small Shelly Fauna - Early Cambrian = small phosphatic or carbonate fossils, disarticulated parts of shells + skeletons Stage 3: Large Animals - Mid-Cambrian Explosion of organisms |
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Burgess Shale
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Located in the Canadian Rockies of BC
- exceptional preservation of the soft parts of fossils - one of the earliest fossil beds containing soft parts |
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What is the Fossil Bias?
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The fossil bias is the disproportionate amount of hard bodied organisms preserved in the fossil record. This is because soft bodied organisms (mostly belonging to Pre-Cambrian biota) are not preserved due to their physical makeup.
- Rock record is filtered through biochemical makeup - Although soft bodied organisms often made tracks/ trails, these are a lot harder to correlate than actual skeletons |
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Cambrian Explosion: WHY?
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Physical environment: oxygenation allowed evolution of complex organisms, chemistry of oceans allowed skeletons to be secreted
Ideal environments: changes in continental configurations, ocean currents and climate, epeiric seas across cratons Skeletons may have evolved through increased predation + support for soft tissues |
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What is one important aspect of sea level in the Ordovician?
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Global sea levels reached some of the highest positions ever
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Ordovician Marine Life
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Cephalopods = main predator
Rugose Corals Tabulate Corals Crinoids/ Bryozoans Trilobites |
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Early forays onto land
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The first evidence of plants colonizing the land comes from the Cambrian
- Probably from a marine sister group (green algae) Trace fossils from beach sandstones suggest that animals occasionally crawled onto land as early as the Cambrian |
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Ordovician Glaciation
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At the end of the Ordovician, global temperatures dropped + ice caps expanded
- Quick and catastrophic effect on climate - Drop in sea level (Epeiric seas are very vulnerable to sea level) |
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Caledonian orogeny
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Silurian-Devonian orogenic activity that affected western Europe from the British Isles through Scandanavia
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Acadian orogeny
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Orogenic activity during the Devonian along the Appalachian margin of Laurentia
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Silurian
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Glaciation at the end of the Orodovician
- Trilobites still important |
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Silurian Fish
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Marine life underwent an ecological arms race between predator and prey
- Rise of jawed fish |
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When did the complete transition to land by plants + animals occur?
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Started at the end of the Silurian and completed by Devonian
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Joggins Formation
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The entire food chain of the terrestrial "Coal Age" ecosystem is represented at Joggins, from the plants to invertebrates + tetrapods
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Permian-Triassic Extinction (P-T Boundary)
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More than 80% of all marine species extinct
- Fusing od continents into Pangea reduced the area of epeiric seas - Sea level dropped roughly 100 m |
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Triassic Marine Life
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- Everything was large
- SCLERATINIAN CORALS - Reptiles in sea = Triassic/ Jurassic |
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Plesiosaur
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Triassic reptile
Marine, broad body, paddle like limbs |
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What three land vertebrates appeared during the Early Triassic?
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- Amphibians (frogs)
- Turtles - Primitive Archosaurs - crocodiles - phytosaurs - pterosaurs |
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When did the rifting of Pangea occur?
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Late Triassic through Jurassic
- Best displayed in the rift formations in eastern N.A |
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Ichthyosaurs
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Reptiles that could not leave the water to lay eggs
- Bore young live - Looked similar to dolphins- convergent evolution |
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Jurassic Planktic Marine Life
- Why are phytoplankton useful for understanding interglacial environments? |
Phytoplankton called coccolithophorids = calcareous nanoplankton that have platelets of calcium carbonate
- Platelets fall apart when the plankton dies and falls towards the sea bed (creating limestone/ mudstone which can then be analyzed) |
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Dinosaurs
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Characterized by upright posture, legs below the body, skill with two openings behind the eye.
Two major groups: Saurischian: archosaur characterized by a lizard like hip Ornithischian: Mesozoic archosaur characterized by a bird-like hip. Most species were herbivores |
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Saurischian Dinosaurs: Theropods
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A clade of saurischian dinosaur with a bipedal gait + teeth adapted for carnivory
- Warm blooded - Includes birds |
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Saurischian Dinosaurs: Sauropodomorphs
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Herbivores
Quadrupedal - Some of the largest animals to ever live on land (may have been for protection, may have limited heat loss |
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Ornithischian Dinosaurs
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Range from the late Triassic to the end of the Cretaceous
- mostly herbivores - Protoceratops, triceratops |
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Hadrosaurs
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Wide toothless bills similar to ducks
- Hollow crests on their skull with extending nasal passages (maybe for improved smell/ sounds) |
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What is the significance of archaeopteryx?
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Oldest known bird fossils
Jurassic - Related to theropods - Feathers = asymmetrical arrangement along a central shaft; suggests a flight function compared to other feathered dinosaurs |
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Pterosaurs
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Late Triassic-Cretaceous
- Earliest vertebrates known to have evolves powered flight - NOT DINOSAURS |
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When did sea level reach its highest?
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Cretaceous
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Mosasaur
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appear around 90 million years ago
- Ate Ammonites |
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True/False:
Dinosaurs ruled the land during the Cretaceous |
Yes! But mammals were on the uprise (placentals/ marsupials)
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When did angiosperms evolve?
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Close to the Jurassic-Cretaceous transition
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Bolide Impact (Chicxulub crater)
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Bolide= at least 10 km in diameter
- Created a crater more than 180 km long located at the northern tip of the Yucatan - The impact of a bolide from outer space at the end of the Cretaceous may have crippled already fragile ecosystems - Created Pg-K boundary |
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What is meant by a transgression/ regression? What conditions are needed for them to occur? How does Walther's Law help us understand the stratigraphic representation of these processes?
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Transgression: Rise in sea level + submergence of a continent under water
Regression: A drop in sea level, + withdrawal of water from the land Conditions: - Glacio-Eustacy - The addition/ loss of glacial weight, either brought on by formation or melting of glaciers - Tectono-Eustacy (basin shape changes) - Physical changes in the basin due to tectonic movement - Sea-floor spreading rate (Quick rates = crustal uplift = changing the shape of the basin) - Sedimentation Rates - More sediment = less room for water = relative sea level rise Walther's Law: In an unbroken sequence, vertically superimposed lithofacies were laterally adjacent at the time of deposition -Walther's law can help us understand the series of transgressions and regressions because we can determine depositional environments through lithofacies analysis, and subsequently figure out SL change through correlating depositional environments + adjacent rock formations For example, at the Jolley Cut we identified t |
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Walther's Law
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In an unbroken sequence, vertically superimposed lithofacies were laterally adjacent at the time of deposition
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Discuss the facies expected in an estuary environment:
Landward/ Brackish/ Seaward |
Estuary
- Gradational increase in sediment deposition while leaving the estuary - Landward: Gravel-sand sized particles with mud, crossbedded, reverse graded - Freshwater shells Brackish Estuary: Sand/mud particles, crossbedded with bioturbation + graded - Ripples, organic rich Seaward: mostly sandy, crossbedded + bioturbated, marine shells |
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Discuss the facies expected in a marsh environment
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- Intertidal area
- Marshes grow at sea level: very important sea level indicator - Silts + muds = low energy - produce laminated shales Vegetation forms peat (baby coal) |
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Describe the factors contributing to sea level change
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Global
- Glacial Eustacy: The balance of water is locked up in land ice vs. oceans. Glacial eustacy is the largest global factor of sea-level change (changes up to 120 m). - Tectono Eustacy: Affects the shape + volume of basins through plate tectonics (convergence/ subduction). Ocean floor spreading rates are also important factors because the faster the sea floor is spreading, the higher the crust will well up (reducing basin capacity). - Sedimentation Rate: Filling of ocean basins with land sediments is a slow + minor wat of changing ocean basin volumes Regional - Isostacy: Sedimentary/ Hydro/ Glacial The loading of sediment/ water/ ice onto a land surface will cause the crust to subside (sink) causing relative sea level to change. Alternatively, the erosion/ evaporation/ melting of these loads can cause isostatic rebound. - Tectonic Changes: uplift + subsidence due to tectonic processes, compression, faulting/ folding/ tilting Compaction: Arises from introduction of infrastructure |
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What major evolutionary features define the Eras of the Phanerozoic? Describe all major trends + their linkage with geological processes
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- Evolution of skeletons, advanced behaviour, radiation of marine + terrestrial life
- Arthropods are an indicator fossil for the paleozoic Paleozoic Cambrian - Aquatic Cambrian Explosion - Burgess Shale (soft bodied organisms) Ordovician - Adaptive radiation of marine life - Reef communities (rugose/tabulate) contribute to limestone/ bioclastic rock - Jawed Fish Silurian - Vascular plants on land - Transition onto land Devonian - Age of fish (lobe-finned/ray-finned) - first angiosperms Carboniferous - Terrestrial life - Amphibians - Pangaea Permian - Trilobites Extinct - Terrestrial amphibians Mesozoic Triassic - 2 major extinctions (start and and) create large boundaries in the rock record - Dinos starting Jurassic - Age of Reptiles - Pangaea starting to split Cretaceous - Small mammals - K-Pg boundary (large boundary in rock record) Cenozoic Paleogene - Age of mammals (no more dinos) Neogene - Early hominids - Grasses + prairies = more food |
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What are the different types of unconformities, and how can you differentiate them in the rock record?
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An unconformity is a surface of separation between two strata that marks an interruption in sedimentation
- This is often an erosional event - Also an extinction event (such as K-Pg boundary) Angular unconformity: A break in sedimentation followed by a disturbance of the strata + sub-areal erosion - Horizontally parallel strate are uplifted and tilted Disconformity: Withdrawal of sea followed by erosion, but now accompanies by folding - unconformity between parallel layers Paraconformity: Disconformity is a parallel bedding plane Blended unconformity: disconformity with no distinct separation (often seen in paleosoils) |
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What are ways in which one can correlate stratigraphic units from location to location?
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Stratigraphic units can be correlated in different locations by comparing: - Rock type (regional)
- Formations (regional) - Fossils (global) Principle of Original Horizontality: Sedimentary deposits are nearly horizontal + parallel to Earth's surface Geochronology: Dating of rocks using radioactive decay of isotopes. This is a form of absolute dating. Rock unite can be correlated using relative/ absolute dating techniques, the lithostratigraphy, or chronostratigraphy Hierarchy of terms: Supergroup-Group-Formation-Member-Bed Biostratigraphy: zoning of stratigraphic layers according to relative time of deposition using ranges of fossils - Animals that were abundant + went extinct (relatively) quickly are the most useful indicator fossils Chemostratigraphy: Correlation of strata using chemical isotopes Sequence Stratigraphy: Based on correlation of unconformities Magnetostratigraphy: Using reversals in the polarity of Earth's magnetic fields (metals in rocks line up N-S at formation) |
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What evolutionary innovations occurred leading up to the start of the Phanerozoic?
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Early animal + plant prokaryotes/ eukaryotes
- Animal life - Predator/ prey interaction - Primitive skeletons The evolution of multi-cellular life occurred when a single-celled prokaryote failed to digest another and produced the first symbiotic eukaryote. This started the precedent for the evolution of all life. Very primitive skeletons evolved and helped small animals by providing protection from elements and predators The evolution of microscopic soft bodied organisms before the Cambrian Explosion *Read Chapter 12h |
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What famous Canadian fossil deposit was found in black shales? How/why were the fossils preserved?
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Burgess Shale, BC
The Burgess Shale is a Cambrian fossil deposit in the Rocky Mountains of Canada. The black colour of the shales indicates an anoxic environment. A large amount of soft bodied organisms have been preserved in thinly laminated shale. The placement of the organisms is underneath what was once an ancient continental shelf. These organisms were quickly buried in an anoxic zone at the bottom of the shelf due to a turbidity current/ landslide event that caused copious amounts of sediment to be quickly washed down the slope. The anoxic environment and quick burial have resulted in almost perfectly preserved laminations of organisms. |
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What covered most of Laurentia during the Paleozoic? What kind of environment was it, and what were some of the major groups?
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An epeiric (inter-cratonic) sea covered most of Laurentia in the Paleozoic. It was a warm shallow sea that was very conducive to life.
Marine biota include: - Cephalopods - Arthropods - Corals (rugose/ tabulate) - Brachipods - Crinoids/ Bryozoans - Bivalves |
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Describe + discuss the major evolutionary changes that occurred during the early-mid Paleozoic, which forever changed the nature of the stratigraphic record?
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Skeletons/ complex animal behaviour.
The origin of endo and exoskeletons was a major development in the history of life. The evolution of skeletons forever changed the rock record because the new calcium phosphate/ calcite/ aragonite skeletons were more likely to be preserved, leading to a greater range of knowledge of ancient organisms, as well as what is known as the "fossil bias" (abundance of hard-bodied organisms in the rock record). The formation of skeletons + shells (specifically in sponges/ corals) also allowed for the formation of bioclastic rocks such as limestones and chert nodules formed from calcite/aragonite/ silicate skeletons. Evolution of more complex behaviour created bioturbation tracks + trails which were more diagnostic of behaviour Moreover, the formation of skeletons allowed for greater + further predator/prey interaction, which introduced myriads of fossils (and index fossils), creating diversity in the fossil record. |
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What cause the mass extinction at the end of the Cretaceous? (K-Pg boundary)
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A bolide 10 km in diameter smashed into the ocean around Mexico's Yucatan Peninsula. This created an immense amount of damage to the Earth's surface, ultimately creating a 180 km wide crater in the Gulf of Mexico. Shockwaves were felt around the Earth, and immense storms radiated around the continents (creating a 3 year winter). This was the most prominent aspect of the dinosaur extinction, and the impact is though to have been the "nail in the coffin" for an ecosystem already in decline.
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Lagerstatten are deposits that contain an extraordinary fossil abundance. Describe + discuss two prominent Lagerstatten examined in the course + how they formed.
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Burgess Shale, B.C
- The Burgess Shaleis a deposit of Cambrian soft-bodied organisms preserved in the black shale of the Rockies. The organisms were deposited at the bottom of a large continental shelf. Taphonomy suggests that this deposit was the result of a large turbidite down a continental shelf. The many preserved biota were washed down into an anoxic zone + quickly covered by falling sediment. The lack of oxygen + quick burial resulted in the perfect preservation of these animals. Rancho La Brea, California This is a large deposit of Pleistocene animals. The Rancho La Brea Tar Pits are an area of land where oil + tar naturally seep up from the host rock. Eventually, the top becomes covered by debris, which causes the danger to be covered up. Animals become trapped one by one (herbivores venture in looking for food, carnivores follow them in and then get trapped). This tar pit has been preserving animals for thousands of years. Animals such as mammoths, dire wolves, sabre-toothed cats, and giant |
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What is the advantage of deep ocean basin sediments for the reconstruction of glacial/interglacial climate change in the Cenozoic? What types of fossils can be used for this purpose?
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Deep ocean sediments contain millions of planktic skeletons that have accumulated over millions of years. Taking a deep ocean core from Cenozoic period rocks would reveal the microfossils of forms of planktic formanifera. These tiny species are/ were sensitive to water temperature (there were different species present for different water temperatures, and their shell coiled specifically as a result of temperature). Moreover, oxygen and other chemical isotopes in the shells reflect changing chemical composition of the water. The paleoenvironment can be relatively reconstructed using these fossils.
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