peripheral motor neuron. Etymology: Gk, periphereia + L, motor, mover; Gk, neuron, nerve. an effector neuron located outside the central nervous system, usually in a ganglion of the sympathetic or parasympathetic nervous system.
Gneiss rock is further characterized by its alternating light and dark bands of minerals. Gneiss forms from volcanic rock, shale, or granitic. Quartz is typically abundantly found in gneiss. The bands that form on gneiss rock are due to the various rocks that are a part of its make-up. The use of the word gneiss dates back to the mid-1700s. Gneiss rocks that originate as sedimentary rock are called paragneiss and those originating as igneous rock are called orthogneiss. Limestone can change into calcareous gneiss which contains calcium carbonate.
The rocks that result from these processes often have ribbonlike layers and may have shiny crystals, formed by minerals growing slowly over time, on their surface. Examples of this rock type include gneiss and marble. Igneous. Igneous rocks are formed when magma (molten rock deep within the earth) cools and hardens.Sometimes the magma cools inside the earth, and other times it erupts onto the surface from volcanoes (in this case, it is called lava).he rocks that result from these processes often have ribbonlike layers and may have shiny crystals, formed by minerals growing slowly over time, on their surface. Examples of this rock type include gneiss and marble. Igneous. Igneous rocks are formed when magma (molten rock deep within the earth) cools and hardens.