Study of Earth history / Geologic Time

Geologic Time

Geologic time video link: http://www.ucmp.berkeley.edu/education/explorations/tours/geotime/gtpage1.html

Expected outcomes:

Vocabulary:

uniformitarianism

paleontologist

contacts

formation

superposition

original horizons

truncated

cross-cutting relationships

paleo, meso, ceno, zoic

physical continuity

correlation

dendrochronology, varve

fossil

half-life

radioactive decay

isotope

era, period, epoch

revolution, disturbance

relative time, numeric time

shield

Concepts:

The divisions of geologic time - four eras and periods of each

Principles used to determine relative age (separate regions(3) and same region(3))

Principles used to determine numeric age

Five types of fossils

Label diagram of relative time principles

Major events of geologic periods

NOTES

Geologic Time - Study of physical history of earth

Geologic time scale - calendar of events

divided using eras - major portions and periods - smaller portions

ears divided by revolutions - times of extensive changes, and disturbances - smaller less significant change

Relative time - putting events in order according to sequence

uniformitarianism - the present is the key to the past - the way things happen today, happened the same way in the past

contacts - the surface that separates two different rock layers

formation - bodies of rock with distinct characteristics that make it distinguishable (Ex: Bar Harbor Formation - pink granite)

Principles of relative time - determines events in a specific region

Original horizontality - sediments deposited in water will form horizontal layers

Law of superposition - oldest layer is on bottom

Cross-cutting - disrupted is older than the disruption (dykes, sills, truncated(cut off))

Principles of relative time - sequence in different areas

correlation - determining age relationships in different areas

physical continuity - trace a course of rock

similarity of rock types - similar rock types in two different areas, follows superposition

fossils - organisms in sediments in one area match in different area - different continents

Fossils - recognizable remain of past life - help solve mysteries of earth's past

in order to form:

must be protected from bacteria and scavengers

covered quickly

needs hard parts

Five types of fossils

1 - petrified - rocklike, original replaced with minerals

2 - carbonaceous - pressure and heat forces out carbon leaving outline of figure

3 - molds/casts - cavity in rock where shell fell then dissolves

4 - original - ice

5 - trace - tracks and prints

Paleontologist - scientist studies fossils

Numeric Time - giving an actual age to events

dendrochronology - using tree rings - climate conditions, physical conditions - 3000 to 4000 years

varve analysis - study of sediment beds in water (varves), rate at which sediments deposit

radiometric dating - using isotopes to determine age

half-life - the time it takes for half of isotope to breakdown or decay(set rate-carbon14 takes 5730 years)

Geologic Time Scale - calendar used to put events in order

zoic - animal life

paleo - ancient

meso - middle

ceno - recent

Precambrian era - longest 4 billion years

Paleozoic era

cambrian, ordovician, devonian, carboniferous, permian periods

Mesozoic era

triassic, jurassic, cretaceous periods

Cenozoic era

tertiary and quaternary periods