Noun. 1. prefrontal cortex-the anterior part of the frontal lobe. prefrontal lobe. cerebral cortex, cerebral mantle, cortex, pallium-the layer of unmyelinated neurons (the grey matter) forming the cortex of the cerebrum. lobe - (anatomy) a somewhat rounded subdivision of a bodily organ or part; ear lobe.refrontal lobe. cerebral cortex, cerebral mantle, cortex, pallium-the layer of unmyelinated neurons (the grey matter) forming the cortex of the cerebrum. lobe - (anatomy) a somewhat rounded subdivision of a bodily organ or part; ear lobe.
1. igneous rocks: formed by the cooling and hardening of magma (molten rock) from inside Earth. 2. sedimentary rocks: formed by the compaction and cementing of layers of sediment (rock fragments, plant and animal remains, minerals from water) 3. metamorphic rocks: formed by the effect of heat and pressure on other rocks. *Earthâs crust is made-up primarily of igneous rocks.
Clastic sedimentary rocks form when individual grains (the sediment), made by fragments of rocks, minerals, or shells, are cemented together (the clastic sediemntary rock). These are the only type of rock that is NOT made simply of crystals, but rather fragments of other materials, broken and then reassembled together.iochemical sedimentary rocks are formed mostly by the remains (whole or broken) of organisms. These remains can be of different kind and include, but are not limited to, for instance, shells, reefs and corals, structures like echinoids' stems, plant fragments, carbon, and many more.