Pituitary tumors are abnormal growths that develop in your pituitary gland. Some pituitary tumors result in too many of the hormones that regulate important functions of your body. Some pituitary tumors can cause your pituitary gland to produce lower levels of hormones. Most pituitary tumors are noncancerous (benign) growths (adenomas). Adenomas remain in your pituitary gland or surrounding tissues and don't spread to other parts of your body.
A volcanic crater is a circular depression in the ground caused by volcanic activity. It is typically a basin, circular in form within which occurs a vent (or vents) from which magma erupts as gases, lava, and ejecta. A crater can be of large dimensions, and sometimes of great depth.During certain types of climactic eruptions, the volcano's magma chamber may empty enough for an area above it to subside, forming what may appear to be a crater but is actually known as a caldera. crater can be of large dimensions, and sometimes of great depth. During certain types of climactic eruptions, the volcano's magma chamber may empty enough for an area above it to subside, forming what may appear to be a crater but is actually known as a caldera.
Geologic History. Crater Lake partially fills a type of volcanic depression called a caldera that formed by the collapse of a 3,700 m (12,000 ft) volcano known as Mount Mazama during an enormous eruption approximately 7,700 years ago.he caldera has a diameter of approximately 8 km (5 mi) north to south and 10 km (6 mi) east to west, with an approximate depth of 1,200 m (4,000 ft) from the caldera rim to the lake floor. Pyroclastic flows deposited pumice and ash on all flanks of Mount Mazama and in valleys below.