Sequence Earth History - Middle School Earth and Space Science
Card 1 of 25
What is the principle of cross-cutting relationships used for relative dating?
What is the principle of cross-cutting relationships used for relative dating?
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A feature that cuts rocks is younger than the rocks it cuts. Any intrusion or fault must postdate the rocks it disrupts.
A feature that cuts rocks is younger than the rocks it cuts. Any intrusion or fault must postdate the rocks it disrupts.
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Which unconformity type occurs when sedimentary rock overlies igneous or metamorphic rock?
Which unconformity type occurs when sedimentary rock overlies igneous or metamorphic rock?
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Nonconformity. Forms when erosion exposes deep crustal rocks before sediment burial.
Nonconformity. Forms when erosion exposes deep crustal rocks before sediment burial.
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Identify the older layer using superposition: Layer A is above Layer B in an undisturbed sequence.
Identify the older layer using superposition: Layer A is above Layer B in an undisturbed sequence.
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Layer B is older than Layer A. Superposition states lower layers formed before upper layers.
Layer B is older than Layer A. Superposition states lower layers formed before upper layers.
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Which type of unconformity occurs when sedimentary rock overlies igneous or metamorphic rock?
Which type of unconformity occurs when sedimentary rock overlies igneous or metamorphic rock?
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Nonconformity. Forms when sediments deposit directly on eroded crystalline basement rocks.
Nonconformity. Forms when sediments deposit directly on eroded crystalline basement rocks.
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What is fossil succession (faunal succession)?
What is fossil succession (faunal succession)?
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Fossil species appear in a predictable order through rock layers. Evolution creates unique fossil assemblages that mark specific time periods.
Fossil species appear in a predictable order through rock layers. Evolution creates unique fossil assemblages that mark specific time periods.
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What does correlation mean when comparing rock layers from different locations?
What does correlation mean when comparing rock layers from different locations?
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Matching layers by age using fossils, rock type, or sequence patterns. Similar fossils or rock sequences indicate layers formed at the same time.
Matching layers by age using fossils, rock type, or sequence patterns. Similar fossils or rock sequences indicate layers formed at the same time.
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What is an unconformity in a rock sequence?
What is an unconformity in a rock sequence?
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A gap in the geologic record caused by erosion or nondeposition. Missing time represents periods of erosion or when no sediments were deposited.
A gap in the geologic record caused by erosion or nondeposition. Missing time represents periods of erosion or when no sediments were deposited.
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Identify the younger feature: A fault cuts through Layers 1–5 but not Layer 6 above them.
Identify the younger feature: A fault cuts through Layers 1–5 but not Layer 6 above them.
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Layer 6 is younger than the fault. The fault must be older since it doesn't cut through Layer 6.
Layer 6 is younger than the fault. The fault must be older since it doesn't cut through Layer 6.
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Identify the relative age: An igneous dike cuts across a sandstone layer.
Identify the relative age: An igneous dike cuts across a sandstone layer.
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The dike is younger than the sandstone. Cross-cutting principle: the dike formed after the sandstone it cuts.
The dike is younger than the sandstone. Cross-cutting principle: the dike formed after the sandstone it cuts.
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Identify the relative age: Pebbles of granite are embedded in a conglomerate layer.
Identify the relative age: Pebbles of granite are embedded in a conglomerate layer.
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The granite pebbles are older than the conglomerate. Inclusion principle: pebbles existed before the conglomerate formed.
The granite pebbles are older than the conglomerate. Inclusion principle: pebbles existed before the conglomerate formed.
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Which sequence best matches events at an angular unconformity: tilted beds below, flat beds above?
Which sequence best matches events at an angular unconformity: tilted beds below, flat beds above?
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Deposition → tilting/folding → erosion → deposition of flat layers. Angular unconformities require tilting and erosion between deposition events.
Deposition → tilting/folding → erosion → deposition of flat layers. Angular unconformities require tilting and erosion between deposition events.
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Identify the correlation clue: Two distant rock layers contain the same index fossil species.
Identify the correlation clue: Two distant rock layers contain the same index fossil species.
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The layers are the same relative age. Index fossils indicate simultaneous deposition at different locations.
The layers are the same relative age. Index fossils indicate simultaneous deposition at different locations.
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What is the law of superposition used for when sequencing major events in Earth history?
What is the law of superposition used for when sequencing major events in Earth history?
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Ordering events by placing older rocks and fossils below younger ones. Superposition provides relative ages to sequence Earth's geological history.
Ordering events by placing older rocks and fossils below younger ones. Superposition provides relative ages to sequence Earth's geological history.
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What does the principle of inclusions state about rock fragments inside another rock?
What does the principle of inclusions state about rock fragments inside another rock?
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Inclusions are older than the rock layer that contains them. Rock fragments must exist before they can be incorporated into new rock.
Inclusions are older than the rock layer that contains them. Rock fragments must exist before they can be incorporated into new rock.
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What does the principle of cross-cutting relationships state about a fault or intrusion?
What does the principle of cross-cutting relationships state about a fault or intrusion?
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A feature that cuts rock is younger than the rock it cuts. The cutting feature must form after the rock it cuts through already exists.
A feature that cuts rock is younger than the rock it cuts. The cutting feature must form after the rock it cuts through already exists.
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What is the principle of lateral continuity for sedimentary layers?
What is the principle of lateral continuity for sedimentary layers?
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Layers extend sideways until they thin, end, or meet a barrier. Sediments spread out continuously until physical limits stop them.
Layers extend sideways until they thin, end, or meet a barrier. Sediments spread out continuously until physical limits stop them.
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What is the principle of original horizontality in sedimentary rocks?
What is the principle of original horizontality in sedimentary rocks?
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Sediments are originally deposited in nearly horizontal layers. Gravity causes sediments to settle flat when deposited in water or air.
Sediments are originally deposited in nearly horizontal layers. Gravity causes sediments to settle flat when deposited in water or air.
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What is the law of superposition for undisturbed sedimentary rock layers?
What is the law of superposition for undisturbed sedimentary rock layers?
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Oldest layers are at the bottom; youngest layers are at the top. In undisturbed sequences, gravity deposits new sediments on top of older ones.
Oldest layers are at the bottom; youngest layers are at the top. In undisturbed sequences, gravity deposits new sediments on top of older ones.
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Which type of unconformity is an erosional surface between parallel sedimentary layers?
Which type of unconformity is an erosional surface between parallel sedimentary layers?
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Disconformity. Erosion creates a surface between parallel layers of different ages.
Disconformity. Erosion creates a surface between parallel layers of different ages.
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Which type of unconformity forms when tilted or folded layers are eroded and overlain by flat layers?
Which type of unconformity forms when tilted or folded layers are eroded and overlain by flat layers?
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Angular unconformity. Tilting occurs first, then erosion levels the surface before new deposition.
Angular unconformity. Tilting occurs first, then erosion levels the surface before new deposition.
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Which unconformity type occurs when tilted older layers are overlain by flat layers?
Which unconformity type occurs when tilted older layers are overlain by flat layers?
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Angular unconformity. Shows past tectonic activity that tilted rocks before erosion and burial.
Angular unconformity. Shows past tectonic activity that tilted rocks before erosion and burial.
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What is an unconformity in a rock-layer sequence?
What is an unconformity in a rock-layer sequence?
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A surface that represents missing time from erosion or nondeposition. Gaps in the rock record indicate periods of erosion or no deposition.
A surface that represents missing time from erosion or nondeposition. Gaps in the rock record indicate periods of erosion or no deposition.
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What is the principle of inclusions used for relative dating of rock fragments?
What is the principle of inclusions used for relative dating of rock fragments?
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Included fragments are older than the rock that contains them. Rock pieces must exist before they can be incorporated into new rock.
Included fragments are older than the rock that contains them. Rock pieces must exist before they can be incorporated into new rock.
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What does the principle of lateral continuity state about a single sedimentary layer?
What does the principle of lateral continuity state about a single sedimentary layer?
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A layer extends sideways until it thins, ends, or meets a barrier. Sediment spreads out during deposition until physical limits stop it.
A layer extends sideways until it thins, ends, or meets a barrier. Sediment spreads out during deposition until physical limits stop it.
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What is the principle of original horizontality in sedimentary rock layers?
What is the principle of original horizontality in sedimentary rock layers?
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Sediments are deposited in nearly horizontal layers. Gravity causes sediments to settle flat when deposited in water or air.
Sediments are deposited in nearly horizontal layers. Gravity causes sediments to settle flat when deposited in water or air.
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