Identify Rock Layer Patterns - 4th Grade Science
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What does a fault in rock layers show about the sequence of events?
What does a fault in rock layers show about the sequence of events?
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Rocks broke and moved after the layers formed. Faults form when rocks fracture and shift along the break.
Rocks broke and moved after the layers formed. Faults form when rocks fracture and shift along the break.
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What is an unconformity in rock layers?
What is an unconformity in rock layers?
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A gap in the rock record caused by erosion or nondeposition. Represents missing time in the geological record.
A gap in the rock record caused by erosion or nondeposition. Represents missing time in the geological record.
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Which pattern best indicates erosion occurred between two rock layers?
Which pattern best indicates erosion occurred between two rock layers?
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An uneven surface separating older rock from younger rock. Erosion creates irregular surfaces before new deposition.
An uneven surface separating older rock from younger rock. Erosion creates irregular surfaces before new deposition.
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What does a layer containing rounded pebbles (conglomerate) usually indicate?
What does a layer containing rounded pebbles (conglomerate) usually indicate?
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Sediment was carried and rounded by moving water. Pebbles become rounded through tumbling in streams or waves.
Sediment was carried and rounded by moving water. Pebbles become rounded through tumbling in streams or waves.
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What does a fossil-rich layer most directly suggest about the past environment?
What does a fossil-rich layer most directly suggest about the past environment?
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The area once supported many living organisms. Fossils form where life was abundant.
The area once supported many living organisms. Fossils form where life was abundant.
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What does a layer of ash or lava between sedimentary layers indicate?
What does a layer of ash or lava between sedimentary layers indicate?
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A volcanic event occurred during the rock sequence. Volcanic eruptions deposit ash between sedimentary layers.
A volcanic event occurred during the rock sequence. Volcanic eruptions deposit ash between sedimentary layers.
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What does the principle of cross-cutting relationships state?
What does the principle of cross-cutting relationships state?
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A feature that cuts rock is younger than the rock it cuts. Used to determine relative ages of geological features.
A feature that cuts rock is younger than the rock it cuts. Used to determine relative ages of geological features.
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Identify which is older: a rock layer or an igneous dike that cuts through it.
Identify which is older: a rock layer or an igneous dike that cuts through it.
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The rock layer is older than the dike. The dike must be younger since it cuts through existing rock.
The rock layer is older than the dike. The dike must be younger since it cuts through existing rock.
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What does a tilted set of rock layers most strongly indicate about past events?
What does a tilted set of rock layers most strongly indicate about past events?
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The layers were moved by forces after they formed. Tectonic activity can tilt originally horizontal sedimentary layers.
The layers were moved by forces after they formed. Tectonic activity can tilt originally horizontal sedimentary layers.
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What does a repeating pattern of sandstone, shale, then limestone most likely show?
What does a repeating pattern of sandstone, shale, then limestone most likely show?
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The environment changed back and forth over time. Different rock types indicate shifting depositional environments.
The environment changed back and forth over time. Different rock types indicate shifting depositional environments.
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Identify the best evidence that rock layers were once horizontal before being tilted.
Identify the best evidence that rock layers were once horizontal before being tilted.
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Sedimentary layers usually form in flat, horizontal sheets. Sediments settle horizontally due to gravity.
Sedimentary layers usually form in flat, horizontal sheets. Sediments settle horizontally due to gravity.
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Which event happened last if a fault cuts across Layers 1–4 and also cuts a dike?
Which event happened last if a fault cuts across Layers 1–4 and also cuts a dike?
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The faulting happened last. The fault is youngest because it cuts all other features.
The faulting happened last. The fault is youngest because it cuts all other features.
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Identify the relative age: Layer A is below Layer B in undisturbed strata; which is older?
Identify the relative age: Layer A is below Layer B in undisturbed strata; which is older?
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Layer A is older. Applies the law of superposition to determine relative age.
Layer A is older. Applies the law of superposition to determine relative age.
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Which feature is the best evidence of a long time gap: a thick layer or an unconformity surface?
Which feature is the best evidence of a long time gap: a thick layer or an unconformity surface?
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An unconformity surface. Unconformities represent significant time gaps, not just thickness.
An unconformity surface. Unconformities represent significant time gaps, not just thickness.
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Identify the correct order of events: deposition, tilting, erosion, new deposition at an angle.
Identify the correct order of events: deposition, tilting, erosion, new deposition at an angle.
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Angular unconformity formed between old tilted layers and new layers. Shows tilting and erosion occurred before new horizontal layers formed.
Angular unconformity formed between old tilted layers and new layers. Shows tilting and erosion occurred before new horizontal layers formed.
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Which rock-layer pattern most strongly suggests a shoreline moved over time?
Which rock-layer pattern most strongly suggests a shoreline moved over time?
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A gradual change from sand layers to mud layers (or the reverse). Fining upward or coarsening sequences indicate shoreline migration.
A gradual change from sand layers to mud layers (or the reverse). Fining upward or coarsening sequences indicate shoreline migration.
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What does a river canyon cutting through many layers show about changes over time?
What does a river canyon cutting through many layers show about changes over time?
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Erosion removed rock after the layers formed. Rivers cut downward through existing rock layers over time.
Erosion removed rock after the layers formed. Rivers cut downward through existing rock layers over time.
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Which rock type most often forms visible layers that record changes over time?
Which rock type most often forms visible layers that record changes over time?
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Sedimentary rock. Forms in horizontal layers that preserve time sequences.
Sedimentary rock. Forms in horizontal layers that preserve time sequences.
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What is the law of superposition in undisturbed sedimentary rock layers?
What is the law of superposition in undisturbed sedimentary rock layers?
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Older layers are at the bottom; younger layers are at the top. This principle helps determine relative ages of rock layers.
Older layers are at the bottom; younger layers are at the top. This principle helps determine relative ages of rock layers.
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What does a layer made of very fine particles (like shale) usually suggest about past water movement?
What does a layer made of very fine particles (like shale) usually suggest about past water movement?
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Slow or calm water conditions. Fine particles only settle when water is still or slow.
Slow or calm water conditions. Fine particles only settle when water is still or slow.
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