EXTENT AND AGE OF CAP-AU-GRES FAULT. 
CHARLES KEYES. 
On the general geological map of Iowa there are three pecu- 
liarities in the areal distribution of the geological formations 
represented which excite particular attention. They indicate 
that not only has the terranal story not been yet all told but 
that owing to unusual misinterpretation the real facts have been 
unwittingly greatly distorted. One of these features is the 
notable southeastward straight trend of the eastern border of 
the basal Missourian, or Bethany, limestone as it leaves our 
state in Wayne county^ — a direction nearly at right angles to 
that which we would ordinarily expect. 
South of the Iowa boundary, in Missouri, the southeasterly 
trend of the Bethany escarpment is traceable for a distance of 
fully fifty miles. This basal Missourian limestone (Upper Coal 
Measures) is found to extend in a long tongue, cut through 
at several points .by the present streams. Beyond, the trend 
of the Bethany ridge assumes its normal course, that is, south- 
westward, and reaches Kansas City and far to the south finally 
enters Oklahoma. 
Twenty years ago, when I was in charge of the Missouri Geo- 
logical Survey, I discovered the existence of and mapped rather 
carefully this singular eastwardly projecting tongue of the 
Bethany limestone. At that time I did not fully understand 
the real significance of the phenomenon. Recently, in the course 
of professional duties, I found out the cause. Called upon to 
“ match up,” as it were, the '.coal seams of a number of localities 
rather widely separated from one another and irregularly scat- 
tered through several counties along the Iowa-Missouri boun- 
dary-line, so that diamond-drill prospecting could go on under 
check, I spent several days before I came to realize what the 
trouble actually was. In former years whenever I came across 
some puzzling problem I could, so soon as it failed to yield a 
quick solution, and before I tired, drop it instanter and turn to 
some more tractable topic. Now, I had either to find a satis- 
factory answer or admit failure which would spell disaster pro- 
fessionally. Moreover, it was a time when results had to be 
