Lecture 1 Geological Time

Question 1

What is Geological Time?

Answer 1

When things happen over long periods of time like mountains forming

Question 2

How old is the Earth?

Answer 2

4.5 Billion years old

Question 3

How long ago did life begin?

Answer 3

4 billion years ago

Question 4

What signified the beginning of life on Earth?

Answer 4

Microbes evolving and their metabolism having effects on the composition of the oceans, atmosphere and surface sediments/soils

Question 5

What life forms existed before mammals and humans?

Answer 5

Microbes like bacteria

Question 6

What is Stratigraphy?

Answer 6

The study of the layering of rocks

Question 7

What is the Principle of Superposition?

Answer 7

The principle that in stratigraphic succession of undisturbed strata, the oldest layer is at the bottom and successively higher layers are successively younger

Question 8

What is the Principle of Original Horizontality?

Answer 8

The principle that sediment must originally have been deposited in layers that were nearly horizontal and parallel to the surface on which they were accumulating

Question 9

What do tilted rocks indicate according to the Principle of Original Horizontality?

Answer 9

An episode of crustal disturbance after the time of deposition

Question 10

What does the Principle of Original Lateral Continuity state?

Answer 10

That all strata extend in all directions until they terminate by thinning at the margins of the basin and end abruptly against some barrier to deposition, or grade laterally into different kind of sediment

Question 11

What is Uniformitarianism or Actualism?

Answer 11

The idea that if you understand how a process occurs today it gives insight into how the process occurred in the past

Question 12

What are some exceptions to Uniformitarianism/Actualism?

Answer 12

Long term changes ex. Evolution of the atmosphere

Short term changes ex. Catastrophic meteorite impacts

Question 13

What are Unconformities?

Answer 13

Gaps in the geological record that formed because layers were not deposited for some time or layers were removed by erosion

Question 14

What are the 3 types of Unconformities?

Answer 14

Angular, Disconformity, Nonconformity

Question 15

What is a Nonconformity?

Answer 15

A surface erosion that separates younger sedimentary strata above older igneous or metamorphic rocks below

Question 16

What is a Disconformity?

Answer 16

A surface of erosion in which the orientation of older strata, below, are parallel to younger strata above

Question 17

What is an Angular Unconformity?

Answer 17

A surface of erosion between two groups of sedimentary rocks in which the orientation of the older strata, below are at an angle to the younger strata above

Question 18

What is the Principle of Cross Cutting Relationships?

Answer 18

The principle that states the geological feature which cuts another is the younger of the two features

Question 19

With inclusions which portion is always the oldest?

Answer 19

The inclusion

Question 20

What is Bioturbidation?

Answer 20

The process whereby sediments are disturbed by organisms living on or in the sediment

Question 21

What are Formations?

Answer 21

A package of rocks that are identifiable and different from the rocks around them

Question 22

What is the Principle of Biologic Succession?

Answer 22

A principle that states that the life forms of each age in earth history were unique for particular periods, and that these unique fossil assemblages could allow geologists to correlate contemporaneous formations around the world