Unit 4 - Fossils & Age of The Earth Flashcards
What is strata?
layers of sedimentary ricks
Where are the oldest layers on this geologic timeline?
at the bottom of
On most geologic time scales like this, how old are the oldest rocks?
4.6 billion years old
______________________ is the belief that geologic processes happen slowly today, just as they have always happened in the past. _______________________ is the belief that most of the geologic features we see today are the result of large scale catastrophes such as earthquakes and floods.
uniforminism
catasrophisum
What are index fossils?
rocks that are unique to a single layer of rock and is used to tell wwhat time period the other rocks are in
What types of creatures are most commonly found as fossils in the fossil record?
hard shelled cratures
How is a fossil mold formed?
impression made by shell/bone
How is a cast formed?
sediment fills the mold
How does an organism become petrified?
fossil decomposes and slowly spaces are filled by mineral rich water
How does it become permineralized?
organism decays then mineral filled water disolves , mineral seeps into cells
What types of organisms (or parts of organisms) are most often found carbonized?
feathers leaves
What are trace fossils?
fossils leave evidence of life
What is a gastrolith? What is a coprolite?
smoothe stone dino stomach, fossilized poop
In which type of rock – sedimentary, metamorphic or igneous – are fossils formed?
sedimentary
How does igneous rock form?
magma cools and solitifies
