DISCOVERY OF VOLCANIC ASH IN IOWA 
CHARLES KEYES 
Of all geological phenomena represented in Iowa those illus- 
trating volcanic action are the rarest. Although we already know 
of the presence of very ancient lava-flows, which are disclosed 
in deep-well drillings, these are associated with rocks very much 
older than any outcropping in the state. These are the Keewena- 
wan porphyries of the Northwest. From that very ancient date 
to the present there is not the slightest sign of volcanic activity 
discernible in all our very full geologic record. The finding, a 
short time ago, in the city of Des Moines, of very considerable 
beds of typical volcanic ash is therefore a circumstance of more 
than passing interest. 
The ash is that pumaceous glass variety which, during violent 
volcanic eruptions, is thrown high in the air and wafted far 
abroad on the wings of the wind.. The material is an impalpably 
fine dust. In the instance of Krakatoa, in the Straits of Sunda, 
Fig. 2. Appearance of volcanic ash under the microscope. 
