Short answers, pulled from the story.
Conglomerate is a sedimentary rock made up of rounded gravel-sized pieces of rock surrounded by finer-grained sediments. The larger fragments within conglomerate are called clasts, while the finer sediment surrounding the clasts is called the matrix. These clasts and matrix are typically cemented by calcium carbonate, iron oxide, silica, or hardened clay.
The distinction between conglomerate and breccia lies in the journey the rocks have taken. If the gravel clasts that comprise it are largely well-rounded to subrounded, it is a conglomerate. If the gravel clasts that comprise it are largely angular, it is a breccia.
Conglomerate formations stand as testaments to geological history across the globe. Examples include Montserrat near Barcelona, the Crestone Conglomerate in Colorado, cliffs on the east coast of Scotland, and the Copper Harbor Conglomerate in Lake Superior. Slabs of conglomerate have also been found on Mars at an outcrop named Hottah.
Geologists classify conglomerates by the specific rocks and minerals that make up the clasts. A conglomerate consisting of a single rock or mineral is known as monomict or oligomict, while one with two or more different types is known as polymict. If the clasts are significantly different from the enclosing matrix, the conglomerate is known as extraformational, and if they are consistent with the matrix, it is known as intraformational.
Conglomerates are deposited in a variety of sedimentary environments including turbidites, fluvial environments, alluvial fans, and glacial deposits. In fluvial environments, conglomerates are typically well rounded and poorly sorted, while glacial deposits known as tillites are typically poorly sorted and matrix-supported.
Metamorphic alteration transforms conglomerate into metaconglomerate. This process subjects the rock to intense heat and pressure, often flattening the original clasts and creating a new texture known as a foliation.