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Difficulty: MediumRocks, Minerals, and Soil

Over thousands of years, weathering breaks down exposed cliffs into mineral particles that are transported by rivers and deposited into a lake basin. As successive sediment layers accumulate above, the underlying grains are compressed and naturally bound together by precipitated minerals. What geological process describes this transformation of loose sediment into solid rock?

  1. A
    Crystallization from rapid cooling of molten lava
  2. Lithification through compaction and cementationAnswer
  3. C
    Regional metamorphism under intense heat and directional pressure
  4. D
    Complete melting into magma within the Earth's mantle

Answer

Lithification through compaction and cementation
The correct answer accurately identifies lithification, which is the two-step geological process involving physical compaction (squeezing out water and reducing pore space under sediment weight) and chemical cementation (mineral precipitation acting as natural glue) to turn loose sediments into solid sedimentary rock.

Step-by-Step Solution

1
Identify the initial geological material and conditions described in the scenario.
Loose rock fragments and mineral grains (sediments) are deposited in layers in a basin.
Sediments originate from weathering and erosion of pre-existing rock.
2
Determine the physical and chemical processes acting upon the accumulated sediment layers.
Overlying weight exerts pressure (compaction) and mineral-bearing groundwater precipitates binding crystals between grains (cementation).
These combined actions convert loose aggregate into consolidated rock.
3
Match these specific processes to their correct geological classification term.
The entire transformation sequence from loose sediment to solid sedimentary rock is termed lithification.
Lithification directly encompasses both compaction and cementation.

Key Concept

Sedimentary rock formation and lithification
Estimated Time:1m 0s
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Topics

Rocks, Minerals, and Soil

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