The term subarachnoid hemorrhage (SAH) refers to extravasation of blood into the subarachnoid space between the pial and arachnoid membranes. SAH constitutes half of all spontaneous atraumatic intracranial hemorrhages; the other half consists of bleeding that occurs within the brain parenchyma.
Definitions and images to illustrate geological terms, links to images and website articles. Assimilation is that process of magmatic differentiation whereby ascending magmas evolve chemically by recruiting easily melted or dissolved components (fusibles) from the walls of their conduits. Under the agency of heat and magmatic fluids, ascending magmas pick up volatiles, silica, trace elements, and occassionally fragments of wall rock.
Weathering. Weathering is the alteration and breakdown of rock minerals and rock masses when they are exposed to the atmosphere. Weathering processes occur in situ, that is, in the same place, with no major movement of rock materials involved.Weathering is a fundamental Earth process. Weathering changes rocks from a hard state, to become much softer and weaker, making them more easily eroded.eathering & Erosion-Introduction to Geomorphological Processes. Geomorphology is the study of the nature and origin of landforms, particularly of the formative processes of weathering and erosion that occur in the atmosphere and hydrosphere.