Beaumont has of late greatly multiplied the number of successive periods of instantaneous upheaval, admitting at the same time that occasionally new lines of upthrow have taken the direction of older ones.
Dikes and faults are denominated upthrow or downthrow, according to the position they are met with in working the mine.
A, B obviously does not change the direction; but C, D is a downthrow dike of a certain number of fathoms towards the rise of the basin, and E, F is an upthrow dike likewise towards the rise.
Only a walk of a few hundred yards atop the upthrow of the low rise revealed the fact that it was in reality the lip of a bench, and that beyond it the country fell away in sheer cliffs whose ultimate drop was some fifteen hundred feet.
The other side of the semicircle was occupied by the upthrow of a low rise blocking off an horizon at its nearest point but a few hundred yards away.
The throw of the fault then changes considerably within little more than half a mile, from 18 feet to zero and again to 20 feet, the undulation so formed producing a large pool (h) entirely on the upthrow side of the fault.
The upthrow is uniformly on the eastern side of the fault.
For the next half-mile, the river keeps to the upthrow side of the fault, the scarp of which blocks the tributary streams from the west, forming a number of small pools.
The pool is simply due to the reversal of the natural slope of the river-bed, caused by the formation of a roll or undulation in the ground on the upthrow side of the fault.
Faults crossing folded strata cause the outcrops to approach on the upthrow side of a syncline and tend to separate the outcrops of an anticline (figs.
The rock on that side of a fault which has dropped relatively to the rock on the other is said to be upon the downthrow side of the fault; conversely, the relatively uplifted portion is the upthrow side.
