Unit 2 Lesson 1

Question 1

Uniformitarianism

Answer 1

James Hutton proposed this theory in the late 1700’s

Geologic processes that happened in the past can be explained by current geologic processes . Geologic changes can be gradual (slow) or sudden (fast)

Example processes like volcanos and erosion that happen today also happened in the Past

Question 2

Fossils

Answer 2

Traces or remains of an organism that lived long ago.

They are most commonly preserved in sedimentary rock

2 groups of fossils: trace fossils and body fossils

Question 3

Ways that organisms become preserved as fossils ( Body Fossils)

Answer 3

A. Trapped in amber. Amber is formed when hardened tree sap is buried and preserved in sediment
B. Trapped in asphalt - which is sticky, thick tar which hardens. Organisms can be trapped
C. Buried in rock - organisms become buried in sediment. Then the sediment over time becomes rock. Bones and shells will become part of the rock
D. Become frozen - in very cold places animals that die may become frozen and preserved
E. Become petrified - when an organism’s tissues are replaced by minerals

Question 4

Trace fossil

Answer 4

A fossilized structure that is formed in sedimentary rock by animal activity or in soft sediment
Examples: footprints, burrows, animal dung

Question 5

Fossil record

Answer 5

All the fossils that have been discovered on Earth

Shows part of the history of life on earth

Question 6

What can fossils tell us?

Answer 6

1. About environmental changes over time
2. How life forms have changed over time

Question 7

How do scientists classify sedimentary rock

Answer 7

Composition - what it’s made of

Texture - tells the environment of the sediment

Features like ripples marks - tell us the motion of wind or water over the sediment

Features like mud cracks - show that an ancient lake or stream was part of an area

Question 8

Climate

Answer 8

Describes the weather conditions in the area over a long period of time

Determined by temperature and precipitation

Question 9

Ice core

Answer 9

A long cylinder of ice obtained from drilling through ice caps or sheets.

Question 10

How do we study how climate has changed over time?

Answer 10

Trees. - tree rings tell us the age of the tree. Thick rings mean growing conditions were good. Thin rings mean that there were poor growing conditions

Sea floor sediment- the chemical composition and microorganisms in sediment tells us the climate when the organisms were alive

Ice cores - tell us the amounts of precipitation in the past