Sandstone (Wikipedia)
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks.Shale (Wikipedia)
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2Si2O5(OH)4) and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite. Shale is characterized by its tendency to split into thin layers (laminae) less than one centimeter in thickness. This property is called fissility. Shale is the most common sedimentary rock.- Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth’s surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles to settle in place. The particles that form a sedimentary rock are called sediment, and may be composed of geological detritus (minerals) or biological detritus (organic matter). The geological detritus originated from weathering and erosion of existing rocks, or from the solidification of molten lava blobs erupted by volcanoes. The geological detritus is transported to the place of deposition by water, wind, ice or mass movement, which are called agents of denudation. Biological detritus was formed by bodies and parts (mainly shells) of dead aquatic organisms, as well as their fecal mass, suspended in water and slowly piling up on the floor of water bodies (marine snow). Sedimentation may also occur as dissolved minerals precipitate from water solution.
- Harlan Ellison (Wikipedia)
Harlan Jay Ellison (May 27, 1934 – June 28, 2018) was an American writer, known for his prolific and influential work in New Wave speculative fiction and for his outspoken, combative personality. His published works include more than 1,700 short stories, novellas, screenplays, comic book scripts, teleplays, essays, and a wide range of criticism covering literature, film, television, and print media. Some of his best-known works include the 1967 Star Trek episode “The City on the Edge of Forever”, considered by some to be the single greatest episode of the Star Trek franchise (he subsequently wrote a book about the experience that includes his original teleplay), his A Boy and His Dog cycle (which was made into a film), and his short stories “I Have No Mouth, and I Must Scream” and “‘Repent, Harlequin!’ Said the Ticktockman”. He was also editor and anthologist for Dangerous Visions (1967) and Again, Dangerous Visions (1972). Ellison won numerous awards, including multiple Hugos, Nebulas, and Edgars.