Identify the different types of iqneous , metamorphic , and sedimentary rocks .

1. The 2 different types of iqneous rocks are intrusive and extrusive . Intrusive iqneous rocks develop within the earth from maqma and extrusive rocks develop outside the earth from lava . 2 . Foliation is a geologic term that is used to describe the banded or layered appearance of metamorphic rocks .

2 . Foliated metamorphic rocks such as gneiss display banding and regrouping of its mineral constituents as a result of enormous pressures and heat. The banding forms perpendicularly to the direction of pressure. The pressure is usually related to tectonic plate collisions. Schist is another type of foliated rock that exhibits thin layering of micaceous minerals, once again due to pressure and heat. The difference between these two types of foliated rock lies in the rock from which they were derived.

Non-foliated metamorphic rocks such as quartzite and marble do not display the banding or layering that are present in foliated rocks. This is because their parent rock was usually sedimentary and more pure in mineral composition than the parent rocks of foliated rocks.

3 . Sedimentary rocks are formed by the accumulation of sediments. There are three basic types of sedimentary rocks: 1) clastic sedimentary rock such as breccia, conglomerate, sandstone and shale, that are formed from mechanical weathering debris; 2) chemical sedimentary rocks such as rock salt and some limestones, that form when dissolved materials precipitate from solution; and, 3) organic sedimentary rocks such as coal and some limestones which form from the accumulation of plant or animal debris. Pictures and brief descriptions of some common sedimentary rock types are shown below.