Principle of original horizontality

• unreformed sequence of sedimentary rocks, each bed is older than the one above
• layers of sediment are generally deposited in a horizontal position
• fragments of one rock unit that have been enclosed within another
• geologic features that cut across rocks must form after the rocks they cut through

Principle of cross-cutting relationships

•  geologic features that cut across rocks must form after the rocks they cut through
•  fragments of one rock unit that have been enclosed within another
• layers of sediment are generally deposited in a horizontal position
• unreformed sequence of sedimentary rocks, each bed is older than the one above

What are  Molds and Casts?

• shell or another structure buried in sediment then dissolved by groundwater, a mold is created
• indirect evidence of life
• fine sediment encasing an organism, over time pressure squeezes out liquid and gases and a thin carbon layer is left behind
•  harden resin of ancient trees

What  is  Amber?

• harden resin of ancient trees
• shell or another structure buried in sediment then dissolved by groundwater, a mold is created
• indirect evidence of life  Tracks, burrows, coprolites(fossilized scat), gastroliths (polished stomach stones)
• mineral-rich groundwater permeates porous tissue (bone/wood), minerals will fall out of solution and fill pores

What  are  Trace Fossils?

• indirect evidence of life  Tracks, burrows, coprolites(fossilized scat), gastroliths (polished stomach stones)
•  harden resin of ancient trees
• mineral-rich groundwater permeates porous tissue (bone/wood), minerals will fall out of solution and fill pores
• shell or another structure buried in sediment then dissolved by groundwater, a mold is created

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What  are  Index Fossils?

• widespread geographically and limited to a short span of geologic time
• 1700s specific types of fossils found in certain sedimentary layers and not in others
• Fossils document the evolution of life through time
• Allows us to recognize what intervals of time are not represented by strata and thus missing from fossil record

Which fossil is a replica of the original shape of the organism?

• cast
• mold
• trace
• preserved remains

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How old do Paleontologists believe the Earth is?

• 2015 years old
• 3.6 billion years old
• 4.6 billion years old
• 4.6 million years old

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The Geologic Time Scale is a record of what?

• old geologists
• sweet geology music
• the known history of rocks and fossils
• a list of every living thing ever

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A bug stuck in amber is an example of what type of fossil?

• cast
• mold
• trace
• preserved remains

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