814Compare fossils found in

sedimentary rock to determine their relative age.

Compare fossils found in sedimentary rock to determine their relative age.

Compare fossils found in sedimentary rock to determine their relative age.

Compare fossils found in sedimentary rock to determine their relative age.

I. Fossils

A.Fossils – the preserved remains or traces of once

living organisms

1.Remains – any part of the organism is a fossil

a. example; bones, teeth, horns, even soft tissue

2. Traces - any imprint, footprint, tooth mark, tail

mark, scratch mark

a. not part of the actual animal but evidence the

animal has been there

Compare fossils found in sedimentary rock to determine their relative age.

II. Dating fossils

A.Absolute dating – the exact age in years that a fossil has

existed

1.Example; 25,000 years or 65 million years

B.Relative dating – a comparison of the ages of different

fossils

1.only tells which is older or younger not a specific

number of years

Compare fossils found in sedimentary rock to determine their relative age.

III. Fossil formation

A.Steps of fossil formation

1.The organism dies

2.the remains are rapidly buried in sediment

3.over time the sediment that covers the organism is

compacted and cemented to become sedimentary rock

4.The layers of sedimentary rock above the remains

eventually erode and the fossil is exposed

Compare fossils found in sedimentary rock to determine their relative age.

IV. Superposition

A.Superposition – the rock layers nearer to the surface are

younger than deeper rock layers

1.“younger over older”

2.Since the more shallow layers of rock are younger than

deeper layers of rock, then the fossils found in more

shallow rock layers are younger than the fossils found in

the deeper layers of rock.

3.This allows you and scientists to tell which fossils and thus

which animals lived first, next, and so on.

Compare fossils found in sedimentary rock to determine their relative age.

Compare fossils found in sedimentary rock to determine their relative age.

Compare fossils found in sedimentary rock to determine their relative age.