Final answer:
Sandstone is a medium-grained, clastic sedimentary rock often red in color due to the presence of hematite. It's commonly found in beds with varying textures and may contain quartz, feldspar, or lithic grains. Bedding and sedimentary structures like cross-bedding can be visible in outcrops.
Step-by-step explanation:
The student's question is about a type of clastic sedimentary rock, specifically sandstone. This rock is characterized by medium grain size, mostly composed of sand-sized quartz grains with medium roundness. The presence of red coloration can be attributed to iron oxide content, typically hematite, which doesn't require a large percentage to impart a rich red hue. Sandstone can exhibit various sedimentary structures, like cross-bedding and, although fossils are less common than in shales, they can present.
Furthermore, sandstone is a soft rock compared to igneous equivalents and can be found in layered beds. In terms of composition, in addition to quartz grains, it may also contain feldspar grains, lithic fragments, and sometimes organic material. The texture of sandstone may vary, ranging from granular and gritty if composed mostly of sand and silt, to fine-grained and compact. Bedding or stratification is a commonly observed feature in sandstones, and its granularity can provide insights into the environment of deposition and transport history of the sediment.
Given these characteristics, we can say that sandstone is an essential geological material, evident in many natural formations around the world, and its study offers insights into Earth's sedimentary processes.