Answer
Based on the information provided, the most likely site from which the sandstone was derived is "Site 2: An outcrop of granite at the previous field trip stop up the road." The sandstone's characteristics, such as being poorly sorted and rich in feldspar and quartz, are consistent with sediment derived from a granite source.
Work Step by Step
Based on the information provided, the most likely site from which the sandstone was derived is "Site 2: An outcrop of granite at the previous field trip stop up the road." The sandstone's characteristics, such as being poorly sorted and rich in feldspar and quartz, are consistent with sediment derived from a granite source.
Explanation:
1. Poorly sorted: Poorly sorted sedimentary rocks indicate that the sediments were not transported over long distances. They are usually derived from nearby sources where the energy for transportation was relatively low. In contrast, well-sorted sediments are typically transported over longer distances, leading to better sorting of particle sizes.
2. Rich in feldspar and quartz: Granite is a type of igneous rock composed primarily of feldspar, quartz, and other minerals. When granite weathers and undergoes erosion, the feldspar and quartz are more resistant to weathering and tend to be concentrated in the resulting sediments. This enriches the sandstone in feldspar and quartz content.
The name given to this type of sandstone, which is derived from granite and rich in feldspar and quartz, is "Arkose." Arkose is a type of detrital sedimentary rock that contains more than 25% feldspar and significant amounts of quartz. It forms when the weathering and erosion of granitic rocks produce sediments that are subsequently compacted and cemented to form sandstone. The presence of abundant feldspar and quartz in the sandstone is characteristic of arkose.
