372 TJic American Geologist. December, i899 
A NOTABLE RIDE. 
From Driftless Area to iowan Drift. 
liy Samuel Calvin, Iowa City, Iowa. 
There is in eastern Iowa one short journey which shows 
a more interesting variety of land forms in smaH space than 
can be seen ahnost anywhere else. It shows too, in a typical 
way, the different surface aspects of areas belonging respective- 
ly to the driftless area and to the plains of Kansas and Iowan 
drift. For these reasons the journey referred to should become 
famous, and might well become a standard in certain particu- 
lars, among students of Pleistocene deposits and topographic 
forms. The journey is over the Illinois Central railroad, it 
begins at Dubuque, and it may end at Dyersville. The whole 
distance does not exceed thirty miles. 
At Dubuque the topography is that of the driftless area, 
and the topographic forms are determined by the effects of 
erosion on the massive, dolomitic, cliff-forming Galena lime- 
stone. In and around the city the Galena has been sculptured 
by atmospheric and other agencies into numerous picturesque 
towers and castles and mural precipices ranging from fifty to 
two hundred feet in hight. There are bold salients standing 
out prominently, like jutting headlands, between the lateral 
gorges cut in the Mississippi bluffs, and residences perched 
airily on their summits seem at first sight to be altogether 
inaccessible. Deep lateral valleys and ravines afford the only 
practicable routes for highways of every sort leading tO' the 
higher levels west of the city; and all these, for some distance, 
follow tortuous courses and ascend at very steep grades. The 
railway uses the valley of Catfish creek as the sinuous pathway 
whereby it is enabled to make the four hundred feet of ascent 
necessary to reach the upland plain at Peosta. From Dubuque 
almost to Julien the fantastically weathered crags and castles 
of Galena limestone, and the steep-sided hills littered with 
loose fragments of the dolomyte partially embedded in the 
thin, residual soil, are prominent features of the landscape, 
and at the same time are easily understood characteristics of 
the driftless area topography. The "Three Towers," massive 
columns of dolomyte forty to fifty feet in hight, rising from 
the comparatively level bottom of the stream valley, are seen 
a short' distance west of Rockdale; and in the same neighbor- 
