Question

Describe how the granite of a mountain could change first into sandstone and then into quartzite. 8. describe how a collision between continental plates can result in the formation of metamorphic rock. 9. describe the rock cycle

Answer 1

Granite is an intrusive igneous rocks made up of different minerals. Granite is made of crystals of biotite, feldspar (orthoclase and plagioclase) and quartz. As weathering acts on the rock it is broken down. Quartz is the most resistant of all the minerals that make up granite and so it will be left after thousands of years of exposure to the processes of weathering and erosion. The main component of sandstone is quartz and it is formed when the weathered sediments leftover from the weathering of the granite rock gets deposited and compacted by the process of sedimentation.
Quartzite is a metamorphic rock formed from sandstone. Sandstone can change into quartzite if it is exposed to extreme heat and pressure inside the crust.
Continental collision occurs when two continental plates move towards each other, each plate being dragged along by convection currents in the mantle. The extreme pressure and heat along these collision zones can cause metamorphism. Granite rocks at these zones can become foliated and change into gneiss.
The rock cycle shows possible paths and processes which crust material (rock)can be subjected to. The three main types of rocks represented on the the cycle are igneous, sedimentary and metamorphic. Igneous rocks are formed when magma or lava cools and hardens. Sedimentary rocks are formed when deposited sediments gets buried, compacted and cemented into hard rock. Metamorphic rocks are formed when preexisting rocks get subjected to extreme temperatures and pressure in the crust.