The effects of orogenic movements so obvious everywhere in all mountainous regions rapidly lose their more salient characteristics as the distance increases from the heart of the system to the more level, plain-like districts above which they rise. In the lowland plains, such as exist in the Mississippi basin, the corrading power of running water is reduced to a minimum, and profound secular decay or heavy glacial accumulations obscure almost completely everything except the most prominent structural features. Indications of low folds or shallow synclines are often visible in this region, but dislocations of strata are rarely found. That the latter are much more frequent than is perhaps generally supposed, subsequent considerations will show. The phenomena here recorded apply more especially to the western interior coal basin occupied in part by Iowa and Missouri, as in this district most of the observations were made.
Carboniferous Basin of the Mississippi . . .