Historical:New Richmond Sandstone
H. B. Willman and T. C. Buschbach
The New Richmond Sandstone (Wooster, 1882, p. 106) is named for New Richmond, St. Croix County, Wisconsin.
The New Richmond Sandstone is equivalent to the lower part of the Roubidoux Formation in Missouri.
Extent and Thickness
The New Richmond Sandstone is well exposed along Franklin Creek, Lee County, and along the Fox River, west of Sheridan, La Salle County (Willman and Templeton, 1951). The New Richmond is present in the north-central and west-central parts of the state (fig. O-10). It is more than 100 feet thick in an area extending south-southwest from La Salle County to Jersey County, and it exceeds 150 feet in southern La Salle County. It is eroded from northernmost Illinois, and it wedges out southward and eastward.
The New Richmond Sandstone overlies the Oneota Dolomite and is overlain by the Shakopee Dolomite. The contact at the base of the New Richmond is locally unconformable. The upper contact is transitional, and the New Richmond appears to grade upward and laterally into the Shakopee.
The New Richmond is sandstone with some interbedded sandy dolomite. The sandstone is white to light gray, fine to medium grained, subrounded to rounded, friable, moderately sorted, cross bedded, and ripple marked. The dolomite is sandy, light colored, fine grained, and contains oolitic chert. The characteristics of the dolomite are similar to those of the overlying Shakopee Dolomite. The heavy mineral suite in the New Richmond is characterized by abundant tourmaline and the presence of garnet (Willman and Payne, 1943).
WILLMAN, H. B., and J. N. PAYNE, 1943, Early Ordovician strata along Fox River in northern Illinois: Journal of Geology, v. 51, p. 531-541.
WILLMAN, H. B., and J. S. TEMPLETON, 1951, Cambrian and Lower Ordovician exposures in northern Illinois: Illinois Academy of Science Transactions, v. 44, p. 109-125; Illinois State Geological Survey Circular 179, 1952.
WOOSTER, L. C., 1882, Geology of the lower St. Croix district: Wisconsin Geological Survey, v. 4, p. 99-159.
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