You find a rock with visible layers of different-colored material and what looks like a shell impression. Which rock type is it most likely?
AIgneous — the layers are from different lava flows
BMetamorphic — the layers are from pressure alignment
CSedimentary — the layers are from sediment deposited over time, and fossils are most common in sedimentary rocks
DIt could be any type — you cannot tell from these clues alone
Layers of sediment and fossil impressions are strong indicators of sedimentary rock. While metamorphic rocks can have bands (foliation), they would not contain well-preserved fossils because the heat and pressure of metamorphism would distort or destroy them.
Question 2 Short Answer
A rock has large, interlocking crystals of several different minerals that you can see clearly without a magnifying glass. What does this texture tell you about how the rock formed?
Think about your answer, then reveal below.
Model answer: The rock is most likely an intrusive igneous rock that cooled slowly deep underground. Slow cooling gave the minerals time to grow into large, visible crystals. A rock like granite has this texture.
Large crystal size is the hallmark of slow cooling. The key word is 'interlocking' — the crystals grew into each other like puzzle pieces as the magma slowly solidified, which is different from the rounded grains you see in sedimentary rocks.
Question 3 True / False
Color is the most reliable property for identifying a rock.
TTrue
FFalse
Answer: False
Color is one of the least reliable properties. Granite can be pink, white, or gray. Sandstone can be red, tan, or white. The same rock type comes in many colors depending on its mineral content and chemical impurities. Texture, grain size, hardness, and how the rock breaks are all more reliable than color.