Geology and Paleontology. 533 
it was held in check for a time, but eventually bursting across and 
rushing with amazing rapidity, it covered in its course over 120 
acres of fine “pasture” lands. All communication between 
INTERMITTENT WELLS IN Nesraska.—In looking over the April 
Naturatisr I was glad to see the facts concerning these wells so 
authoritatively stated. A few years ago, while examining the geol- 
ogy of that region, I learned something concerning them, but did 
not have time to investigate them as I wished. I now have no 
doubt ot the facts and little concerning their explanation. 
The region is table land slightly sloping toward the south-east, 
‘way from the Platte river, which flows along its northern mar- 
gin. Its geological structure is quite uniformly, as follows: 
egg ee 2-3 feet. 
A yellowish clayey soil (typical loess) stas GO- 
enn, a a aa a A T aa rt 
A reddish, coarser loess-like clay A eT o ™ 
Sand, with some Bravei, Jere Foe een ee ones Oren rE 40-60 “ 
The underlying rock is unknown, but probably belongs to the 
Niobrara group. It is not unlikely that Bowlder clay underlies 
ve Sand considerably, for it is well developed a little east of David 
cty, and judging from the depth of wells I infer that its surface 
slopes gradually toward the west, nearly to Shelby, if not beyond. 
. The belief of the farmers of the region, “that the water-level 
n these wells corresponds to the level of the Platte river, I do 
not hesitate to Say, is correct. I was once quite skeptical about it, 
but Careful examination of scores of cases in Polk, York, s 
Surface of this lake must not be conceived as a true level, be- 
rause its southern side is drained by the numerous streams whi 
_ Pidly eastward, but such variations are not very apparent. I 
l few cases permanent water is found in wells above this 
Ee Where we may suppose a local basin-shaped deposit of clay. 
This Subterranean circulation of water was first announced by 
