3IO The American Geologist. November. 1902 
The Gh^cial Drift may l)c mentioned here because it enters 
with the Carboniferous formations into the problem of drain- 
age by artificial sinks. Xo emendation to the description by 
MacBride (op. cit. ]). 13'^).) of the double glacial sheet need 
be offered and in fact his interpretation of it depends on wider 
observation than could be made within the covinty, except as 
to the fact of an older and a younger coextensive deposit sep- 
arated in general by a gravelly surface coating upon the deep- 
er one. The existence of an old glacial drift which had been 
eroded and the burial of this under a younger similar deposit, 
the inequalities of which form a still young glacial topog- 
raphy, is a point of interest in the question of drainage. 
The Drainage problem. This region has two systems of 
drainage which Prof. MacBride has described (op. cit. p. 120- 
121.), both of which are imperfectly developed and require to 
be artificially extended. The one is by surface channels and 
the other by natural sinks. For the greater part the many 
small glacial drift basins formerly were not drained or they 
overflowed merely into marshy "runs." there not having been 
time enough since the glacial retreat to erode deep channels 
upon so level a surface. Also the artificial ditches which 
now aid the drainage are kept open not without some difficul- 
ty on account of sluggish intermittant flow of water, while 
also successful draining of the higher lands may cause flood- 
ing of the lower. Tiling is much used to keep the fields dry, 
and successfully when the water thus collected can be turned 
away by ditches and sinks. Xatural sinks which have been 
used as the recipient of the artificial field drainage have served 
with such high degree of efficiency that artificial borings also 
have been tried where sinks are wanting, as MacBride has 
alreadv written. Some of these have failed. This system has 
been developed seemingly without the aid oi geologists. 
The part of Hvimboldt County which lies west of the 
East river can use this system evidently, and possibly it may 
be much extended. It is worth the while therefore to enter 
farther into the scientific explanation of success and failure. 
It is not thought here practicable to offer a complete solution 
to the problem but the direction in which it is to be sought 
may be indicated a little more nearlv than heretofore. Re- 
calling firsth' that this area has evidentlv those rock forma- 
