All flashcards
Flashcard 1: What evidence from rocks and fossils best supports that a landscape has changed over time?
Answer: Different fossils and sediments in different layers showing changing environments. Each layer tells a different environmental story.
Flashcard 2: What does a rock layer made of very fine, thin sediments most strongly suggest about past water conditions?
Answer: Calm water, such as a lake bottom or deep ocean. Fine particles settle only in still water.
Flashcard 3: Identify what matching the same index fossil in two locations suggests about the layers.
Answer: The layers formed during the same time period. Index fossils existed everywhere briefly.
Flashcard 4: What is a trace fossil, and what does it show about an organism?
Answer: Tracks, burrows, or droppings; shows behavior and activity. Evidence of movement, not body parts.
Flashcard 5: What does it suggest if plant fossils are found in a rock layer above marine fossils?
Answer: The environment changed from ocean to land over time. Different fossils show environmental shifts.
Flashcard 6: What is an index fossil, and why is it useful for comparing rock layers?
Answer: A widespread, short-lived fossil; helps match ages of rock layers. Same species = same time period globally.
Flashcard 7: What is uplift, and how can it help explain marine fossils found high above sea level?
Answer: Raising of Earth’s crust; it can lift seabed rocks to higher elevations. Tectonic forces push rock layers upward.
Flashcard 8: Identify the most likely cause if a canyon cuts through many rock layers in one area.
Answer: Long-term river erosion cutting down through rock layers. Rivers carve deep valleys over millions of years.
Flashcard 9: What does the Law of Superposition state about undisturbed rock layers?
Answer: Lower layers are older; higher layers are younger. Sediments deposit chronologically, creating a time sequence.
Flashcard 10: Which option best explains matching fossils in the same type of rock on two separated hills?
Answer: The hills were once connected before erosion separated them. Erosion carved valleys between once-continuous rock formations.
Flashcard 11: Identify the relative age: A rock layer cuts across other layers as an intrusion; is it older or younger?
Answer: Younger than the layers it cuts through. Cross-cutting relationships show intrusions form after existing layers.
Flashcard 12: What is a fossil?
Answer: Preserved remains or traces of a living thing from long ago. Forms when organisms are buried and minerals replace organic material.
Flashcard 13: Identify the relative age: A fossil in a lower layer is compared to one above it in undisturbed rock.
Answer: The lower-layer fossil is older. The Law of Superposition shows older rocks beneath younger ones.
Flashcard 14: What does a fault in rock layers show?
Answer: Rocks broke and moved due to Earth forces. Tectonic stress creates fractures where rock masses shift position.
Flashcard 15: What is a sedimentary layer?
Answer: A band of rock made from sediments pressed and cemented. Forms when loose sediments compact under pressure over time.
Flashcard 16: Which event is most likely if rock layers are bent or tilted instead of flat?
Answer: Tectonic forces changed the land after the layers formed. Plate movements can fold, tilt, or uplift originally flat layers.
Flashcard 17: What is a trace fossil?
Answer: A preserved sign of activity, such as tracks, burrows, or droppings. Shows ancient behavior without preserving the actual organism.
Flashcard 18: Which rock type most often forms in layers and can contain fossils: igneous, sedimentary, or metamorphic?
Answer: Sedimentary rock. Forms from compressed sediments, preserving organisms between layers.
Flashcard 19: Which rock layer is older in an undisturbed stack: top layer or bottom layer?
Answer: Bottom layer. According to superposition, oldest layers settle first.
Flashcard 20: Which process most directly creates new sediment layers: weathering, erosion, or deposition?
Answer: Deposition. Sediment must settle to form new layers.
Flashcard 21: What does a layer of rounded pebbles (conglomerate) most strongly suggest about past conditions?
Answer: Fast-moving water, such as a river or stream. Flowing water rounds rock fragments by tumbling.
Flashcard 22: Which option best indicates a layer formed in a desert: coral fossils or sand dune patterns?
Answer: Sand dune patterns. Sand dunes form in dry, windy environments.
Flashcard 23: What is a rock layer (stratum)?
Answer: A single layer of rock formed during a specific time period. Each layer represents different environmental conditions.
Flashcard 24: Which type of rock most often contains fossils?
Answer: Sedimentary rock. Fossils form when organisms are buried in sediment layers.
Flashcard 25: What is sedimentary rock?
Answer: Rock formed when layers of sediment are pressed and cemented. Layers build up over time and harden under pressure.
Flashcard 26: Identify the relative age: Layer A is above Layer B in undisturbed rock. Which is younger?
Answer: Layer A is younger. Superposition shows upper layers formed more recently.
Flashcard 27: Which evidence best supports that a canyon formed over time: one sudden crack or many eroded rock layers?
Answer: Many eroded rock layers. Canyons form through gradual erosion over millions of years.
Flashcard 28: What does it mean if rock layers are bent or folded?
Answer: The layers were changed by strong pressure in Earth’s crust. Tectonic forces can deform originally flat layers.
Flashcard 29: What is a fault?
Answer: A crack in Earth’s crust where rocks have moved. Movement along faults can cause earthquakes.
Flashcard 30: What is uplift?
Answer: Slow raising of Earth’s crust that can form higher land. Tectonic forces push land surfaces upward.