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40 Cards in this Set
- Front
- Back
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Uniformitarianism |
physical processes that operate in the modern world also operated in past, at roughly the same rates, and these processes were responsible for forming geologic features preserved in outcrops Basically states the present is the key to the past |
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Difference between relative and numerical age
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Relative-the age of one feature with respect to another in a sequence
Numerical-age of a feature given in years |
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Principle of original horizontality
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layers of sediment, when first deposited, are fairly horizontal because sediments accumulate on surfaces of low relief(such as sea floor) in a gravitational field
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Geologic Time: Eons, Eras, Periods, Epochs |
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Cambrian explosion |
sudden diversification in life, with many new types of organisms appearing over a relatively short interval |
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Isotopic Dating |
or radiometric dating, process geologists developed by using radioactive elements to calculate numerical ages of rocks |
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Radioactive decay |
-radioactive isotopes are unstable and undergo this change which converts them to a different element and an take place by a variety of reactions that change atomic number of the nucleus and form a different element |
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Isotopes |
different versions of an element, have same atomic number but different atomic weight Parent isotope-isotope that undergoes decay Daughter isotope-decay product Half-life-how long it takes for half of a group of parent isotopes to decay |
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Taxon |
group of related organisms Hierarchy from broadest to narrowest: Kingdom, Phylum, Class, Order, Family, Genus, Species (Kings Play Chess On Fine Gray Sand) |
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Taxonomy |
field of biology that classifies living and extinct organisms according to set of rules |
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Phylogeny |
the evolutionary history of a species or group of species *Phylogenetic tree is a hypothesis that depicts evolutionary relationships among groups of organisms *Species and their most recent common ancestor form a clade within a phylogenetic tree |
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Different types of ancient life preservations |
Trace fossils-include footprints, feeding trees, burrows, and dung that organisms leave behind in sediment Body fossils-tar and syrup act as preservatives and hardens organisms into amber |
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Anoxic conditions |
If organism settles into oxygen-poor environment, oxidations reactions happen slowly, scavenging organisms aren’t abundant, and bacterial metabolism acts slowly so fossilization is possible |
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Biostratigraphy |
identification of fossils found within sedimentary rock strata as method of determining relative geologic age of rock |
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Fossil Assemblage |
the distinctive layers of sedimentary rock and the group of fossil species *William Smith realized particular assemblage can be found only in limited interval of strata, and not above or below this interval |
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Natural selection |
those with adaptations suited to the environment will live and reproduce…those not will not pass their genes and become extinct |
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Principle of fossil succession |
Once fossil species disappears in sequence of strata, it is extinct forever
---Provides geologic underpinning for theory of evolution |
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Gradualism (Evolutionary Process) |
evolution happened at a constant, slow rate |
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Punctuated Equilibrium (Evolutionary Process) |
evolution occurs slowly for quite a while (in equilibrium) and then continues very rapidly and factors that could cause this are: 1. Geologic catastrophe causes many species to go extinct leaving many new species to colonize 2. Sudden change in Earth’s climate puts stress on organisms-some survive some go extinct 3. Sudden formation of new environments-rifting splits continent and new ocean with coastlines appearIsolation of breeding population |
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Depositional Environment |
places where early life first evolved and locations where sediment accumulates are burial places that promote fossilization ****Amount and kind of life that lives in the environment is determined by: 1. Chemical composition of the waters and sediments 2. Physical processes of sediment delivery and accumulation 3. Energy of the water flow |
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Marine Environments (deposited at or below sea level) |
Shallow water carbonate environments: Most sediments are carbonates-shells of organisms Warm, clear, marine water, relatively free of clastic sedimentsIn the photic-zone, not muddy, thus photosynthesis can occur |
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Marine Environments (deposited at or below sea level) |
Shallow-marine clastic deposits: finer sands, silts, muds Fine sediments deposited offshore where energy is low Finer silts and muds turn into siltstones and mudstone Usually supports an active biotic community |
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Archean Eon |
(3.8 to 2.5 billion years ago) strata contain stromatolites: first appeared around 3.2 Ga First large fossil structures-layered mounds of sediment Still exist, growing today near Australia Alternating cycles of cyanobacteria and sediment settling from water Origins of life: in the form of cyanobacteria (blue-green algae) |
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Proterozoic Eon |
Life forms evolved slowly after its initial appearance in the Archean Eukaryotes (bacteria with nuclei) evolved around 2.7-2.1 Ga Multicellular life forms appeared by 750 Ma Large life forms leaving obviously recognizable fossils evolved around 620 Ma |
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Phanerozoic Eon |
visible life defined by widespread, diverse life forms beginning with marine invertebrates, followed by vertebrates and colonized on land Carbonate shells, skeletal/bone material enhance preservation First era is Paleozoic and first part of Paleozoic is the Cambrian Period (biological diversification of life shortly after 542 Ma |
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Paleozoic Era |
Breakup of Pannotia into separate landmasses open new ecological niches and stimulated evolution=>barriers of gene flow, isolation of populations Early Paleozoic (Cambrian): sea level rises and falls several times, acting like a giant spoon that stirs the soup (many types of marine environments created=>life evolved) Middle Paleozoic (Silurian): land plants evolve (moss), bony fish, and other marine life, also life arrives on land Off western part of ancestral Appalachians, sediment moved down mountains due to topographic gradient. These sediments accumulated into the epicontinental seas as the Catskill Delta. Sediment carried by river is dumped when velocity drops, grows over time building out into the sea |
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Supercontinents & Ancient Atmospheres (Characteristics of early atmosphere) |
denser than ours and complex life forms could not have survived *Water vapor, nitrogen, methane, ammonia, hydrogen, carbon dioxide, sulfur dioxide probably formed by “out-gassing” from mantle during differentiation and subsequent volcanism Colliding comets may have contributed some gases Volcanic gases created and early atmosphere Liquid water condensed to form oceans Photosynthesis organisms appeared |
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Early Paleozoic |
Vast, shallow epicontinental seas and platform deposits and rifting of Pannotia created: New ocean basins, Siberian craton, Baltica (Europe), Laurentia (North America, Greenland), Gondwana (South America, Africa, India, and Australia), Epicontinental seas Worldwide sea levels rose and fell several times during |
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Early Paleozoic Cont'd |
Paleozoic Transgression-widespread rise in sea level Regression-widespread fall in sea level Taconic orogeny- terrains collied to create pre-Appalachians |
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Mid-Paleozoic |
Silurian “greenhouse” (global warming) melted galciers, sea levels rose, continents flooded -Vast reef complexes in shallow epicontinental seas -New marine species evolved in early Silurian -Acadian orogeny uplifts early Appalachian Mountains |
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Mesozoic Era |
Jurassic to Cretaceous was age of dinosaurs |
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Late Paleozoic (Pre-Mesozoic Era) |
Global cooling and regressing seas initially Epicontinental seas replaced with coastal swamps Continental collisions & formation of Pangea Alleghenian orogeny: final collision of Appalachian uplift (Carboniferous & Permian Periods) |
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End Triassic Extinction (ETE) |
age of the dinosaurs, defines boundary between Triassic and Jurassic **Thought to have been triggered by rapid release of CO2 related to effusion of Orange Mountain Basalt, thus separation of Pangea |
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Ice Age: Present ice age Ice Age of the Quaternary Period Late Cenozoic Era |
2.6 million years ago, but over last 3 billion years, Earth has largely been greenhouse world Pleistocene to Holocene- Since formed, Polar Ice Caps have expanded and contracted but have not melted entirely Animals: wooly mammoth and saber-toothed tiger |
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Basic Factors of long-term change in Earth’s climate |
1. Relationship of tilt, insolation, and latitude or “Milankovitch” variations in Earth’s orbit Earth’s axis precesses (wobbles like a top) over the course of 25,000 years (Precession determines timing of seasons relative to position of Earth along its orbit around the sun) 2. Greenhouse effect CO2 as major Greenhouse Gas->both human and nature can cause climate change |
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External Factors of Long-Term Change in Earth's Climate |
1. Gravitational pull of other planets 2. Sun’s radiation |
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How geologists reconstruct past climates |
Obtaining cores of sediments from bottom of the oceans & Analyzing oxygen isotopes in sediment’s carbonate |
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Cenozoic Epochs |
Holocene-paleolithic ice age to present day Pleistocene- ice age, humans appear Pliocene- neanderthals, cooling, two legs, tools Miocene- warming, apes Oligocene- monkeys, apes Eocene- pro-simians and early monkeys Paleocene- earliest primates (proto-prosimians) |
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Taxonomy Vs. Phylogeny |
Taxonomy focuses more on characteristics that organisms have in common Phylogeny focuses more on evolutionary relationships |
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Evolutionary Events
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Precambrian: No Vertebrates
Paleozoic: Fish/ Amphibians Mesozoic: Dinosaurs/reptiles Cenozoic: Mammals/ Birds |
