 |
Calling
All Rock Detectives! |
| igneous |
Igneous rocks form when melted rock hardens.
There are two types: intrusive, which forms when magma is trapped
deep inside the Earth, and extrusive, which happens when magma
exits and cools, outside of, or very near the Earth's surface,
like in a volcanic eruption. You can tell is a rock is intrusive
or extrusive by looking at the rock. Intrusive rocks are coarse
grained, like granite. Extrusive rocks are fine grained, like
pumice and basalt. |
| sedimentary |
Sedimentary rocks form as the result of
weathering, which breaks rocks into bits, and erosion, during
which the rock bits are carried off and deposited. Sedimentary
rocks are evidence that at one point in time moving water, like
a river or stream, existed. |
| metamorphic |
Formed from sedimentary or igneous rocks
which are changed by heat and pressure. Metamorphic rocks are
evidence of volcanic activity. |
| weathering |
The
process of breaking rocks into silt, clay, and other tiny pieces, called
sediment. Water is an important agent, or cause, of weathering. |
| erosion |
Erosion
is the process of moving sediment from one place to another. Water
is the most important agent of erosion. |
| deposition |
Deposition
is the process of dropping, or depositing, sediment in a new location. |