256 GEOLOGY OF ASPEN MINING DISTRICT, COLORADO. 
To sum up, there are six terms proposed to designate different parts 
of a fault movement, each term applying to a measurement which varies 
in accuracy and proximity to the total displacement in proportion to the 
available amount of information. For general outline work, where accu- 
rate data are not obtainable, the terms throw and vertical separation, 
referrmg to the measurements of a fault at its intersection with a vertical 
plane, and the term heave or offset, indicating a measurement of a fault at 
its intersection with a horizontal plane, are adopted. The throw and 
offset are parts of the actual fault movement, but of unknown value, while 
the vertical displacement sustains a certain relationship to the throw. 
Where more complete data are obtainable, the terms total displacement, 
lateral separation, and perpendicular separation are adopted. The perpen- 
dicular separation sustains a certain relationship to the lateral separation, 
as the lateral separation does to the total displacement. 
