Recognition of Beds of Tertiaric Age in Our state

Iowa has been repeatedly and so thoroughly planed off and worked over by continental glaciers of no less than five great ice-invasions that it could be hardly expected that any remnants of the softer pre-glacial formations, if there ever were any deposited within the state\u27s boundaries, would survive. Moreover, the state is now everywhere so deeply covered by the several till-sheets and the vast eolian soil-mantles as to effectually conceal all traces of the existence of pre-glacial deposits which we ordinarily refer to the Tertiaries