Chapter 2: Sedimentary Rocks Study Set

Why aren't sedimentary rocks found deep in the earth?

Because the higher temperatures and pressures deep in the earth would melt or metamorphose them.

How are bioclastic sedimentary rocks formed?

Bioclastic sedimentary rocks form when fragments from previously living material, or material produced by a living thing, is compacted to form a rock.

How are crystalline sedimentary rocks formed?

By the evaporation of sea water and the precipitation of solids from sea water.

Why are sedimentary rocks the only rocks that contain fossils?

The processes, temperatures and pressures that form other rocks destroy or distort any fossils in them.

How was coal formed?

Coal is formed from the compaction of partially decayed ancient plant material.

What does saturated mean?

Full of. When a solution is saturated it is holding as much of a dissolved substance as it can hold.

Why are sedimentary rocks often layered?

Sediments are deposited in layers that are later compacted and cemented to form rock with the layers intact.

What does precipitation mean when we are talking about sedimentary rocks?

Precipitation is the process of a solids forming in a liquid when a solution becomes too concentrated for minerals to stay dissolved.

Describe the temperature and pressure of formation of sedimentary rocks as compared to other rock types.

Sedimentary rocks form at low temperatures and pressures compared to other rocks because they are made of materials that were deposited and buried at the earth's surface(mostly underwater).

How do sedimentary rocks form?

Sedimentary rocks form primarily by the deposition of sediments under water.

Describe evaporation and precipitation.

When a shallow sea evaporates the minerals dissolved in the water stay behind and the water becomes saturated.If the sea evaporates any more the minerals that are dissolved will be forced to form solid crystals (precipitate).

What is a clast?

a rock fragment

Why are sedimentary rocks found as a veneer (surface layer) over much of earth's surface?

because sedimentary rocks are made of materials deposited in layers at earth's surface.

How are clastic sedimentary rocks formed?

by the burial, compaction, and cementation of clasts (rock fragments)

How are clastic sedimentary rocks classified?

by the size and shape of the clasts they are made up of.

What are the three main types of sedimentary rocks?

clastic, crystalline, and bioclastic

What is the difference between a conglomerate and a breccia?

conglomerates have rounded fragments and breccias have angular fragments.