Gas Wells Near Letts, lowa.— Witter. 319 
Post Glacial Changes. Not the least valuable chapter of the 
book is the discussion of the surface changes which the German 
territory has undergone in postglacial time. Certain criteria, 
which have at one time and another been used as evidence of 
change of level, are discussed and their errors clearly pointed out. 
Evidence of great changes of level in post-glacial time is not 
found inthe coast region. ‘The topographic distribution of the 
loess in southern Germany, so far as its altitude in different 
regions is given, would raise the question whether there may not 
have been considerable surface warping in that region. 
Although I have dissented from some of Dr. Wahnschatfe’s con- 
clusions, some of these differences are more apparent than real, 
because of the diverse use of terms. Others are more funda- 
mental. To accomplish the purpose for which this paper is 
written, it has been necessary to emphasize the points wherein 
American and German views differ most widely, passing over in 
silence many of the more numerous points of agreement. But 
the book is throughout suggestive, and on the whole a most satis- 
factory compendium of present knowledge concerning the glacial 
formations of Germany. 
GAS WELLS NEAR LETTS, IOWA. 
By Pror. F. M. Wirrer, Muscatine, Lowa. 
In the early partof December, 1890, Mr. T. L. Estle, living in 
Section 3, Township 75 N. Range 4 W. 5th Principal Meridian, 
sunk « well on his farm for water. In drift at a depth of about 
100 feet he struck gas which burned readily, but in two or 
three days the gas ceased to flow. Between 40 and 80 rods 
west of this place about the same time Mr. R. M. Lee bored for 
water, At about 100 feet he failed to get water and stopped 
boring. 
Inthe evening he commenced to pull out his casing, and sueceeded 
in raising it perhaps 8 or 10 feet. During the night a great roar- 
ing was heard, and on approaching the well with a lantern the gas 
took fire and a great flame shot several feet into the air with a 
frightful noise. In a few days the flame was extinguished, and 
the gas piped into Mr. Lee’s house, a few rods away, where for 
over a year it has furnished him light and fuel. 
