4 
30 A. L. Fwing—Erosion of Limestone. 
eroded through a ie of 6,000 feet. The valley is 
flanked on either side the remnants of the overlying 
Medina Sandstone which Hh monoclinal ridges from 600 
to 1,000 feet above its floor. tsk inside slopes of these moun- 
contains a Jarge amount of calcium and magnesium salts. That 
fromthe State College well gives *2273 grams per liter of solids, 
over 80 per cent of which are calcium and magnesium carbon- 
ates. Sink holes, caves, etc., are common as in “other limestone 
regions. Still, Il am not aware that any attempts have been 
made to determine the amount of erosion taking place by this 
process, and hence the ohana is submitted. 
verage width of str where the vases were 
taken, 22°86 meters (75 ft). ‘Depth. average of six measurements 
across the bed of the stream, *823 meters (2:7 ft.). This gives 
as the cross-section of the stream 18-81m? (202°5 sq. ft.). 
Allowance she made in these determinations for obstruction 
from weeds, et 
The vaauny: of the stream was determined by floating sur- 
face particles and by floating a pee bottle weighted with shot 
at various depths from ‘3 m. to 75 m. (the greatest depth of the 
stream being 1m.). The serait of the stream was found 
to be 994°776 m. per hour, this giving 18°172m’, as the amount. 
of water removed per hour. The water shows on evaporation, 
as average of two tests, 155°3 grams per m’*, giving 2,905,974 
grams the amount of solids removed per hour, or 25, 456, te 
kilos. per annum. As the area of limestone drained by Spr 
Creek is about 100 sq. miles, this gives 255654 kilos. ‘of rolids 
as the amount pane per annum per sq. mile. This is 
ge pores to 282 to 
A portion of the fess carried off by Spring Creek, a 
falls not upon the limestone area considered above, but u 
the mountains bordering the valley. Probably one-fourth a 
~ water falls bi Be the mountains. To show that the main 
ro 
the valley. Thus not more than one-fortieth of the solids in 
the Spring Creek water probably comes from the mountains. 
