Gas emission topography (GET) is defined as a topography that is peculiar to and dependant upon the emission of methane.  A variety of forms have been identified and associated with GET and these are found in many locations in the oceans of the world as well as on land.  In the Santa Barbara Channel, the forms are typically pock marks and mounds ranging in size from tens of meters in diameter to more than 350 meters in diameter.  At times, the forms take on great complexity when individual forms interfere with one another to form complex gas emission topography.  On land in Ventura County, GET forms include tar flows, gryphones, and salse. 

Form	Description
Mud Volcano	Conical shape from about 100m to several km across.  May be up to several hundred m. high
Mounds	Shield shape from a few m. in diameter to a few hundred m.  May be a few to several tens of m. high
Salse	Less developed type of cone, crater at top filled with mixture of mud, gas (mostly methane), water and at times, tar or oil.  Diameter from less than 1m to about 20 m.
Gryphones (seepage hole)	Pit or seepage hole with diameter of several cm to several m, height to 3m.
Pock Mark (crater, may be elongated)	Steep sided erosional features with diameter of a few m to several hundred m. and depths of a few m. to several tens of m.
Breccia or tar flow	Variable sizes from a few m. to more than 1 km
Complex forms	Mixture, or amalgamation of mounds, pockmarks