2/26/13 1.List the fossils in order from the oldest to the youngest. 2.Explain why you know that is the correct order.

Today I will investigate fossils in sedimentary rock layers to gather evidence of changing life forms.

What is a fossil? The trace or remains of an organism that lived long ago most commonly preserved in sedimentary rock.

How are fossils preserved? Petrification is a process in which minerals replace an organisms tissues. One form of petrification is called permineralizations. Permineralization is a process in which the pore space in an organism’s hard tissue is filled with minerals. Replacement is a process in which minerals completely replace the tissues of an organism.

Petrified Wood This piece of petrified wood was fossilized through replacement.

Types of Fossils Trace fossils- imprints filled with sediments and preserved with rocks.

Mold and Cast fossils

Index fossils

Geologic Time Scale

2. Any naturally preserved evidence of animal activity is called a(n) a. trace fossil. c. index fossil. b. cast. d. mold. 3. A mark or cavity made in a sedimentary surface by a shell or other body is a(n) a. index fossil. c. mold. b. cast. d. coprolite. 1. Fossils found in the bottom layers of sediment are probably older than fossils found in top layers because a. the bottom layers are older than the top layers. b. the bottom layers are younger than the top layers. c. all of the layers are the same age. d. the bottom layers have folded over the top layers 4. An ideal sequence of rock layers containing all of the known fossil and rock formations on Earth is called the a. geographic column. c. geologic column. b. relative column. d. geologic sequence. Fossil Exit Quiz