the compaction and cementation of rock particles forms

The compaction and cementation of rock particles forms sedimentary rocks.

Sedimentary Rocks are formed at or near the Earths surface.75% of crust is covered by sedimentary rocks, yet only 10% of the crust is sedimentary.

Lithification – cementing particles together

involves 2 processes: 1) compaction2) cementation

a) Lime or calcite (bubbles in acid)b) Hematite (rust or iron oxide) – Red Rocksc) Limonite – yellow brown colord) Silica – quartz, hardest of all cementse) Clay – generally, a powder look

3 Types of Sedimentary Rocks

1) Clastic – made from the lithification of rock fragments. 2) Chemical precipitate – from chemicals that form out of solutions3) Organic

A) Clastic – Names are based on particle size.

1) Conglomerate – 50% or more gravel size particles.

2) Sandstone – sand sized particles of quartz

3) Arkose – sandstone made up of primarily feldspar

4) Siltstone – particles you can’t see with a naked eye.

5) Shale – made up of clay, splits into layers, smells earthy when wet.

B) Chemical Precipitates – these form when

1) water evaporates, leaving the dissolved material as a sedimentary rock.

2) Small organisms with shells die, and their shells and other hard parts accumulate to form rocks.

These rocks are named based on their mineral composition.

1) Limestone – made up primarily of calcite, and may contain fossils.2) Coquina – loosely cemented shell fragments made up of calcite.3) Travertine – calcite deposited around hot springs, usually layered in appearance.

4) Chalcedony – from the precipitation of quartz. Very hard rocks!

Varieties of chalcedony:

agate – bandedpetrified woodchert – light coloredflint – dark colored

5) Halite – evaporated saltwater deposit6) Gypsum

These two rocks make up the “evaporites”, and their mineral name is also their rock name.

ofCoquina

Coal