SOME GEOLOGIC ASPECTS OF CONSERVATION 
139 
passing to other fields. It is well known that in the vicinity of 
Dubuque there are many caves, which have been formed by the 
solution of the limestones along cracks and fissures. Some of 
these have yielded beautiful specimens of stalactites and similar 
deposits, as well as great quantities of lead ore, and the caves 
themselves are interesting features. I well remember my disap- 
pointment a number of years ago on going through a cave in the 
City Railway’s park to find that it had been absolutely stripped 
of all its wonderful stalactitic deposits and transformed into a 
bare, ugly, electric lighted tunnel. Its beauty was irredeemably 
gone. Such treatment is nothing short of stupid barbarism. J ust 
west of Dubuque, too, are a number of fine examples of erosion 
pillars which have been carved out of the hard Galena dolomite. 
Some of these may be seen from the Illinois Central trains stand- 
ing guard as lone outposts from the main body which has wasted 
away during the ages. Such remnants bear in themselves witness 
that no glacier has invaded the region during the long ages that 
they have been forming by the slow processes of erosion by the 
ordinary agents. 
Another form of erosion remnant, most unique in a state like 
ours and of great interest anywhere, is the natural bridges of 
Jackson county. These are formed by the incomplete falling in 
of the roof of an underground drainage course, whereby por- 
tions are left still spanning the now open valley. They are lo- 
cated about six miles northwest of Maquoketa and together with 
a large cavern in the ravine they make a very popular resort 
for drives and picnics. 
Outside of the more rugged area of northeastern Iowa there 
are, of course, many isolated spots of great beauty and charm 
which are well deserving of the nature lover ’s attention. Among 
these may be mentioned the Devil’s Backbone, near the north- 
west corner of Delaware county, various localities along the Ma- 
quoketa and Wapsipinicon rivers, the Palisades of the Cedar, 
near Mount Vernon, Devil’s Lane, near Muscatine, Indian 
Spring, near Burlington, and numerous others of equal interest 
and value. Entirely aside from their aesthetic value all of these 
areas are of importance to the geologist because of the illustra- 
tions of natural phenomena which they furnish, and for that rea- 
son as well as for others they are eminently worthy of care and 
preservation. 
