Investigating the Unconformity Remember that the essence of all unconformities is that they are a break in the rock record, which appears to provide little inherent information. However, it does indicate that something significant occurred to change the prevailing environmental conditions that had previously favored preservation. Identifying unconformities in context with the rocks that surround them is an important part of how geologists begin to understand the geologic history of an area Identifying unconformities also means it is important to understand the basic types of roc · Igneous rocks are formed from molten materials that have cooled and solidified and have a more uniform crystalline structure. They can either be extrusive (formed on the Earth's surface) or intrusive (formed underground). Types of igneous rocks include basalt, granite, and andesite . Sedimentary rocks represent accumulation of fragments of preexisting rock that have been broken down by weathering, erosion, or other means The accumulation of fragments may be sorted into layers or compacted with little evidence of layering. Types of sedimentary rocks include sandstone, shale, and limestone. Because of its formation from accumulated fragments, sedimentary rocks are also typically more prone to weathering and erosion than igneous or metamorphic rocks .Metamorphic rocks are any type of rock that has been exposed to heat, pressure, and/or chemical reaction to be metamorphosed (or changed) into another rock type. Slate, gneiss, and marble are examples of metamorphic rocks Sort the descriptive terms into following.
1. prone to weathering
2. shale
3. resistant to weather
4. ingigneous intrusions
5. sedimentary
6. bedding sandstone