Mr. McMath. 
436 DISCUSSION: FORESTS, RESERVOIRS, AND STREAM FLOW 
occasionally enters the cavern, and there is no doubt that the Big 
Spring of the Meramec, several miles distant and on the other side of 
a high rock ridge, is the chief water outlet of the second area. 
The normal flow of the spring is about 60000000 gal. per 24 
hours. A year’s daily record of temperature showed a variation of 
about 2° Fahr., which proves that it is ground-water. At the time 
of the visit, about an hour after the first stream was forded, several 
engineers agreed to estimate the flow at 250000000 gal. per 24 hours. 
The water was roily, but fairly potable, being much the same as the 
water then supplied the citizens of St. Louis after sedimentation 
(since 1904, the St. Louis water has been clarified). The original forest, 
which was not dense, was cut 25 years or more ago for timber and for 
smelting-furnace fuel. Nature seems to be indifferent as to reforesta- 
tion. The humus is very thin, but the soil and subsoil are absorptive 
sponges, probably not less than 60% of the precipitation being stored. 
The third stream, known as the “Water Fork of the Meramec,” has 
no special feature to distinguish it from other streams coming from 
a rugged country whose hilltops are the remnants of a denuded plateau. 
The valleys are narrow, with numerous springs, the rivulet tributaries 
bring in fragments of disintegrated rock to be worn down by attrition 
into gravel and sand for the big city below. At the time of the visit, 
two hours after the spring was reached, the flow was taken to be 
about 400 000000 gal. The water was of a gray turbidity, but became 
potable after 5 min. subsidence in a vessel. Soil wash was not seri- 
ously in evidence. This area has been deforested for timber and 
furnace fuel. The land ownership being largely held by the Iron 
Company, the population is sparse and not given to agriculture. The 
place rock is sandstone above and flinty limestone below, readily dis- 
integrated. The humus is of fair depth on the plateaus and thin on 
the hillsides. The conditions are favorable to absorption; probably 
50% of the precipitation would be a fair estimate. 
The intensity of rainfall may be said to vary from a Scotch mist 
to a cloudburst; the run-off varies accordingly. The absorptive power 
of subsoil and rocks may vary from nothing to totality, and the run- 
off inversely. If the subsoil below the humus is impervious, crops may 
start, but must perish; if pervious, capillary action and roots of plants 
recall much moisture from underground storage, but a very large part 
sinks below reach and feeds springs more or less remote. 
If one regards local run-off as the end, underground water is to 
him a dead loss; if he takes a broader view, it comes back to its place 
among available resources. 
In the locality used by the writer as an illustration, there is fairly 
good basis for the idea that the ground-water gets back to the streams 
within the areas. The locality is in the “Ozarks,” and probably is 
fairly representative of broken country in low mountain districts. 
