A molten rock cools and solidifies. It is later weathered/eroded and the small fragments of the rock are carried to a lake. These small fragments are compressed and cemented to form a new rock. What type of rock is this new rock?

Question

A molten rock cools and solidifies.  It is later weathered/eroded and the small fragments of the rock are carried to a lake.  These small fragments are compressed and cemented to form a new rock.  What type of rock is this new rock?

BlackTom AI · Accepted Answer

Sedimentary rocks form when loose particles (sediments) are deposited, compacted, and cemented together.

1. Relevant knowledge points and concepts
- Igneous rock: forms from the cooling and solidification of molten rock (magma or lava).
- Weathering and erosion: break solid rock into smaller fragments called sediments.
- Sediment transport and deposition: sediments are carried (by water, wind, ice) and laid down in basins such as lakes.
- Lithification: the combined processes of compaction (pressure squeezing out water and reducing pore space) and cementation (minerals precipitating from groundwater and binding grains) that turn sediments into sedimentary rock.
- Metamorphic rock: forms when existing rocks are altered by high heat and/or pressure without melting.

2. Step-by-step reasoning process
- Molten rock cools and solidifies → this produces an igneous rock (initial stage).
- That igneous rock is weathered and eroded → produces small fragments (sediments).
- Sediments are carried to a lake → they are deposited and accumulate in layers.
- Over time, additional sediment buries the layers, increasing pressure → compaction reduces pore space.
- Groundwater moving through the sediment deposits minerals (like silica, calcite, or iron oxides) that act as cement → cementation.
- Compaction + cementation = lithification → formation of a sedimentary rock (for example, sandstone if the fragments are sand-sized, or shale if clay-sized).

3. Calculations
- No numerical calculations are required for this conceptual process; the intermediate steps are the sequential physical processes listed above.

4. Why the correct answer is correct
The description explicitly states that fragments are compressed and cemented after deposition in a lake. Those are the defining steps of lithification that produce a sedimentary rock.

5. Why the other options are incorrect
- "Rock and roll" is a joke and not a geological rock type.
- Metamorphic rock would require substantial heat and/or pressure altering the rock’s mineralogy and texture, not simple compression and cementation of loose fragments.
- Igneous rock forms directly from cooling molten material, not from compacted and cemented sediment.

Conclusion: The new rock produced by compression and cementation of transported fragments is a sedimentary rock, matching the provided answer "sedimentary rock."

A molten rock cools and solidifies. It is later weathered/eroded and the small fragments of the rock are carried to a lake. These small fragments are compressed and cemented to form a new rock. What type of rock is this new rock?单项选择题

类似问题

A rock formed from the bits and pieces of other rocks is a(n):

The sediment within a sandstone is more coarse (i.e. larger) than the sediment within a conglomerate.

Sedimentary rocks form when molten materials solidify.

What sedimentary rock would you expect to fizz in acid?

A rock formed from the bits and pieces of other rocks is a(n):

A rock containing large, rounded cobbles and boulders:

After weathered/eroded sediments are deposited, they may form rock through the process(es) of:

What earth processes form shale?

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单