This paper combines several conclusions which the writer has published elsewhere during the last decade, together with a few that are here presented for the first time, and is an attempt to set them forth as a consistent whole. In order to present a connected story, a few tentative conclusions and even mere guesses are introduced, but are distinctly marked as such. Nearly all the streams mentioned have been more or less personally examined.

Orogenic Movements before the Pliocene

In the later Archean or pre-Cambrian there were evidently upheavals at both ends of the state; in the center of the Black hills and on the east an extension of land from Minnesota between Dell rapids and Sioux falls westward to the James river.

Of the early Paleozoic little need be said, except that there was evidently land in or near the Black hills, as is proved by the occurrence . . .

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