Environment Science Exam Ch 1-4

Front 1

sedimentary structure

Back 1

Any feature of sedimentary rock formed during deposition or by later sedimentary processes- for example, layering, ripple marks, or fossils.

Front 2

bedding

Back 2

Layering that develops as sediments are deposited; also called stratification.

Front 3

cross-bedding

Back 3

A sedmentary structure in which wind or water deposits small beds at an angle to the main sedimentary layering.

Front 4

ripple marks

Back 4

Small, parallel ridges and troughs formed in sediment by wind, water currents, or waves, which are often preserved when the seidment is lithified.

Front 5

mud cracks

Back 5

Irregular polygonal fractures that develop when mud dries, forming patterms that may be preserved when the mud is lithified.

Front 6

sedimentary structure

Back 6

Any feature of sedimentary rock formed during deposition or by later sedimentary processes- for example, layering, ripple marks, or fossils.

Front 7

bedding

Back 7

Layering that develops as sediments are deposited; also called stratification.

Front 8

cross-bedding

Back 8

A sedmentary structure in which wind or water deposits small beds at an angle to the main sedimentary layering.

Front 9

ripple marks

Back 9

Small, parallel ridges and troughs formed in sediment by wind, water currents, or waves, which are often preserved when the seidment is lithified.

Front 10

mud cracks

Back 10

Irregular polygonal fractures that develop when mud dries, forming patterms that may be preserved when the mud is lithified.

Front 11

fossil

Back 11

The imprint, remains, or any other trace of a plant or animal preserved in rock.

Front 12

metamorphism

Back 12

The process by which rocks and minerals change form in response to changes in temperature, pressure, chemical conditions, and/or deformation.

Front 13

metamorphic grade

Back 13

The intensity of metamorphism that formed a rock; the maximum temperature and pressure attained during metamorphism.

Front 14

folliation

Back 14

The layering in micas and other minerals created by metamorphism.

Front 15

slaty cleavage

Back 15

A metamorphic folliation producing a parallel fracture pattern that cuts across original sedimentary bedding in micas or other metamorphic rocks.

Front 16

Mercalli Scale

Back 16

(1902) measure of earthquake destruction

Front 17

Earthquake hazard

Back 17

anything associated with an earthquake that may affect the
normal activities of people. This includes surface faulting,
ground shaking, landslides, liquefaction, tectonic deformation, tsunamis, and seiches.

Front 18

Earthquake risk

Back 18

probable building damage, and number of people that are
expected to be hurt or killed if a likely earthquake on a particular fault occurs.

Front 19

Primary EQ damage

Back 19

a. surface shaking
b. ground rupture
c. differential subsidence
d. liquefaction

Front 20

Secondary EQ damage

Back 20

a. fire
b. landslides and slumps
c. Tsunami

Front 21

mass extinction

Back 21

A sudden, catastrophic event during whciha significant part of all life-forms on Earth become extinct.

Front 22

relative age

Back 22

An approach to mesuring geologic time based on the order in which events occured, but not measured in years.

Front 23

absolute age

Back 23

Time measured in years

Front 24

principle of original horizontality

Back 24

The principle that most sediment is deposited as nearly horizontal beds, and therefore most sedimentary rocks started out with nearly horizontal layering.

Front 25

principle of superposition

Back 25

The principle that in any undisturbed layers of sediment or sedimentary rock, the age becomes progressively younger from bottom to top; younger layers always accumulate on top of older layers.

Front 26

principle of cross-cutting relationships

Back 26

The obvious principle that a rock or feature must first exist beofre anything can happen to it; thus if an intrusion of rock cuts across an existing rock, the dike (intrusion) is younger.

Front 27

principle of faunal succession

Back 27

The principle that species succeeded one another through time in a definite order, so that sedimentary rocks of the same age contain identical fossils and rocks of different ages contain different fossils; therefore, the relative ages of rocks can be identified from their fossils.

Front 28

conformable

Back 28

A term describing sedimentary layers that were deposited continuously without detectable interruption.

Front 29

unconformity

Back 29

An interruption in sediment deposits or a break between eroded igneous and over-lying sedimentary layers, causing a gap in the geological record for that place. Types of unconformities include disconformity, angular unconformity, and nonconformity.

Front 30

disconformity

Back 30

A type of unconformity in which the sedimentary layers above and below the unconformity are parallel.

Front 31

angular unconformity

Back 31

An unconformity in which younger sediment or sedimentary rocks rest on the eroded surface of tilted or folded older rocks.

Front 32

nonconformity

Back 32

A type of unconformity in which layered seidmentary rocks lie on an erosion surface cut into igneous or metamorphic rocks.

Front 33

correlation

Back 33

The process of establishing the age relationship of rocks or geologic features from different locations on Earth; can be done by comparing characteristics of the layers or the the types of fossils found in those layers. There are two types of correlation: time correlation (age equivalence) and lithologic correlation (continuity of the rock unit).

Front 34

index fossil

Back 34

A fossil that dates the layers where it si found because it came from an organism that is abundantly preserved in rocks, was widespread geographically, and existed as a species or genus for only a relatively short time.

Front 35

key bed

Back 35

A thin, widespread, easily recognized sedimentary layer that can be used for correlation because it was deposited rapidly and simultaneously over a wide area.

Front 36

isotopes

Back 36

Atoms of the same element that have the same number of protons but different numbers of neutrons.

Front 37

half-life

Back 37

The time it takes for half of the atoms of a radioactive isotope ina sample to decompose.

Front 38

radiometric dating

Back 38

The process of measuring the abolute age of rocks, minerals, and fossils by measuring the concentrations of radioactive isotopes and their decay products.

Front 39

geologic column

Back 39

A composite, columnar diagram that shows the sequence of rocks at ta given palce or region, arranged to show their position in the geologic time scale.

Front 40

geologic time scale

Back 40

A chronological arrangement of geologic time sub-divided into eons, eras, periods, and epochs.

Front 41

eon

Back 41

The largest unit of geologic time. The most recent eon, the Phanerozoic Econ, is further subdivided into eras.

Front 42

era

Back 42

A geologic time unit. Eons are divided into eras and eras are divided into periods.

Front 43

Precambrian

Back 43

A term referring to all of geologic time befor ethe Paleozoic Era, encompassing approximately the first 4 billion years of Earth's history. Also refers to all rocks formed during that time.

Front 44

Hadean Eon

Back 44

The earliest time in Earth's history, ranging from 4.6 billion years ago to 3.8 billion years ago.

Front 45

Archean Eon

Back 45

A division of geologic time 3.8 to 2.5 billion years ago. The oldest known rocks formed at the bginning of, or just prior to, this eon.

Front 46

Proterozoic Eon

Back 46

The portion of geologic time occuring during a period from 2.5 billion to 543 million years ago.

Front 47

Phanerozoic Eon

Back 47

The most recent 543 million years of geologic time, including the peresnt, represented bby rocks that contain evident and abundant fossil records.

Front 48

Paleozoic Era

Back 48

548 to 248 million years ago. During this era invertebrates, fishes, amphibians, reptiles, ferns, and cone-bearing trees were dominant.

Front 49

Mesozoic Era

Back 49

248 to 65 million years ago. Dinosaurs rose to prominence and became extinct during this era.

Front 50

Cenozoic Era

Back 50

65 million years ago to present