Geogexam1

Front 1

Relative Age

Back 1

Clues to the actual time that the events took place may be present.

Front 2

Outcrop

Back 2

the part of a rock formation that is exposed on the surface of the ground

Front 3

Catastrophism

Back 3

a theory, now discredited, that the geologic features of Earth were formed by a series of sudden violent catastrophes rather than a gradual evolutionary process. A more recent version of this theory holds that the evolutionary process of geologic development has on occasions been supplemented by such catastrophes.

Front 4

Absolute Age

Back 4

The amount of time that has elapsed since the rock formed.

Front 5

Erratics

Back 5

moved from their original location, are now known to have been deposited by glaciers during the last Ice Age were used by Catastrophists as evidence of sudden catastrophic flooding.

Front 6

Superposition

Back 6

ordering of layers; the fossils the rock layers contain and consquently at the heart of relative age dating.

Front 7

Strata

Back 7

Sedimentary rock layers

Front 8

Neptunists

Back 8

Believed a great globe-engulfing sea laid down all of the earth's rocky layers, gradually exposing them as the water slowly receded.

Front 9

Plutonists

Back 9

Neptunists lost their case to Plutonists, who insisted that crystalline rocks such as granite were not chemical precipitates but had crystallized from a molten state.

Front 10

gradualism

Back 10

"Theory of the Earth" by Hutton proposed that the earth is powered by its own internal heat, is in continuous but gradual change, and is constantly decaying, renewing, and repairing itself.

Front 11

Unconformity

Back 11

River Jed-vertical layers of rock worn down by erosion were covered by horizontal beds

Front 12

Cross-cutting relationship

Back 12

younger sequences truncates an older one.

Front 13

Faunal Succession

Back 13

Individual rock layers can be "fingerprinted" and correlated(or traced) from one place to another on the basis of the fossils they contained.

Front 14

Stratigraphic Column

Back 14

Arranging each of the rock layers into a vertical sequence. younger upon older strata

Front 15

Actualism

Back 15

The present is the key to the past

Front 16

Rule of inclusions

Back 16

The rule that holds that fragments of one rock in a layer of another must be older than the layer itself.

Front 17

Rule of Cross-cutting relationships

Back 17

James Hutton-holds true that any feature that cuts across a rock must be younger than the rock it cuts.

Front 18

Stratigraphy

Back 18

Succession of sedimentary strata

Front 19

Paleozoic

Back 19

Ancient Life
-first fish, first land plants, first amphibians & reptiles, abundent coal-forming swamps

Front 20

Mesozoic

Back 20

Middle life
-Pangea, first dinosaurs, break up of Pangea, first mammals, Sierra Nevada, birds, Rocky Mountains, extinction of dinosaurs

Front 21

Cenozoic

Back 21

Recent Life
-Formation of the Alps, Himalayas, San Andreas Fault, earliest Hominids, Ice Age Begins, humans, ice age ends

Front 22

Eons

Back 22

4 largest intervals of geologic time, some with durations of billions of years

Front 23

Archean

Back 23

Primeval
-starts with the Earth's oldest known rocks

Front 24

Proterozoic

Back 24

earlier life, which contains the first record of multicellular organisms and visible life

Front 25

Phanerozoic

Back 25

visible life, during which fossils became abundant.

Front 26

Precambrian

Back 26

Hadeon Eon, Archeon Eon, Proterozoic Eon

Front 27

Periods

Back 27

Named for the periods after places where rocks of that age are found

Front 28

Index fossils

Back 28

Fossils that were useful for the subdivision bc they were easily recognized

Front 29

Epoches

Back 29

Shorter geologic periods

Front 30

Precisions

Back 30

refers to the exactness of an estimate whereas accuracy refers to its correctness

Front 31

Radioactivity

Back 31

Henri Bequerel discovered that the atoms of some chemical elemets are inherently unstable and break down in a predictable fashion.

Front 32

Isotope

Back 32

whenever the number of neutrons in the atomic nucleus of a chemical element varies.

Front 33

Mass Number

Back 33

Isotopes are identified not by their atomic number but by their mass number. The sum of protons and neutrons in their atomic nuclei

Front 34

Parent

Back 34

If the new isotope produced by this radioactive decay is also radioactive, several breakdown steps from the original radioactive parent isotope may be necessary to form the final stable nonradioactive daughter

Front 35

Exponential decay

Back 35

The process whereby the amount of the parent isotope is halved in each successive half life

Front 36

Hadeon Eon

Back 36

The interval between the Earth's oldest rocks and the formation of the planet.

Front 37

Continental Drift

Back 37

Wegener proposed that the continents of Europe, Africa, and the Americas were once joined.

Front 38

Pangea or Pangaea

Back 38

Meaning all lands.
name of the supercontinent

Front 39

Gondwanaland

Back 39

Wegner's reconstruction of the southern continents into a portion of Pangea know refered as Gondwanaland.

Front 40

Magnetometer

Back 40

The resulting magnetic field is very weak but it can be detected and its origination measured with a highly sensitive instrument

Front 41

Paleomagnetism

Back 41

The study and measurement of the Earth's magnetic field from these ancient rocks

Front 42

Polar wander curve

Back 42

The line connecting the changing positions of either pole suggested by successively older basalt samples from a given continent

Front 43

Apparent polar wander curves

Back 43

The polar wander curves only trace apparent (rather than actual) polar movement

Front 44

Magnetic Polarity Reversal

Back 44

Earth's magnetic field periodically reversed itself

Front 45

Magnetic epoches

Back 45

Major magnetic reversals
-every million years or so

Front 46

Magnetic events

Back 46

shorter flips
-lasting a few thousand years to a few ten thousand years

Front 47

Normal Magnetic polarity

Back 47

North ends of all compass needles have pointed towards the north magnetic field

Front 48

Reversed magnetic polarity

Back 48

The north end of a compass end would have pointed toward the South Pole

Front 49

Magnetic anomaly

Back 49

odd magnetic pattern
ex.-the floor of the Atlanic Ocean by Iceland

Front 50

Mid-ocean ridges

Back 50

Mountain chain under the ocean

Front 51

Sea floor spreading

Back 51

Harry Hess
-circulating currents under the ocean floor cause molten rock or magma to ooze up beneath mid-ocean ridges as the sea floor spreads away on each side

Front 52

Pillow lavas

Back 52

Distinctive bulbous flows of lava characteristic of formed submarine basalt adn great fissures in the seabed

Front 53

Deep ocean trenches

Back 53

Narrow curved depressions in the ocean floor that can reach depths of over 11 Kilometers and extend for thousands of kilometers

Front 54

Benioff zones

Back 54

The progressive increase in the depth to the foci of these earthquakes was now seen to reflect the violent descent of oceanic crust back into the Earth's heated interior

Front 55

Focus

Back 55

The point in the earth's interior at which an earthquake is generated