Page:History of Stearns County, Minnesota; volume 1.pdf/31

 scales before mentioned. A shark's tooth was also found by Mr. Kloos in the plastic clay that here forms the bank of the Sauk river.

F. B. Meek, to whom these fossils were submitted, wrote Mr. Kloos as follows: "The specimens ——— consist of Inoceramus problematicus, impressions apparently of Ammonites percarinatus, scales of fishes and a small shark tooth allied to Corax or Galeus. Among the drawings also sent by you, there is one of the inner volutions of Scaphites larviformis, or some nearly allied form. From these fossils, and the lithological character of the bed in which they were found, there can be no reasonable doubt, that it belongs to the Cretaceous system, as well as to the Benton group of the Cretaceous series as developed in the upper Missouri country. As you have suggested, the locality at which these specimens were collected, cannot be far from the eastern limits of the great Cretaceous basin that occupies so much of the country along the Upper Missouri, and it is very desirable that the eastern boundary of this group of rocks should be traced out as accurately as possible, through Minnesota. Owing to the heavy deposits of drift there, however, this will be a difficult task, and can only be done by careful observations of all that is revealed by deep wells and other excavations. Consequently it is important that all the facts brought to light in this way should be carefully noted and published."

Glacial and Modified Drift. Glacial striae observed at Sauk Centre, as before mentioned, bear S. 40 degrees E., referred to the true meridian, being at right angles with the striae noted in Sauk Rapids, Benton county, about forty miles farther east. Nearly all the ledges of Stearns county are planed and worn to a smooth surface by the ice-sheet; but, excepting at Sauk Centre, none of them, so far as seen in this sruvey, retain glacial striae, because of the slight disintegration wrought upon their surface by rains and frost.

The contour and material of the drift deposits have been stated in an earlier part of this chapter. The stages in the recession of the ice-sheet which they indicate are somewhat complex. During the culmination of the last glacial epoch, an ice-current from Lake Superior and northern Wisconsin extended over the east half of this county, to a limit in Luxemburg, Wakefield, northeastern Munson, Farming, Albany, Krain, and northeastern Millwood. In these townships, extending from south-southeast to north-northwest, the ice-current from the northeast, by which the striae in Sauk Rapids were made, was confluent with the ice-current from the northwest, which atriated the rock at Sauk Centre. West of this line of confluence boulders and gravel of limestone abound, derived, like the limestone everywhere present in the drift of western Minnesota and of Dakota, from the limestone strats which have their nearest outcrops in the vicinity of Winnipeg, Manitoba. Fragments of lignite, and very rarely of petrified wood, are also found in this western drift. The drift brought by the ice-current from the northeast is distinguished by the absence of limestone and the presence of boulders and pebbles of igneous and sedimentary rocks peculiar to the region of Lake Superior. A difference in color is also observable, the drift from the northwest and west being dark bluish gray, excepting near the surface, where it 