A somewhat detailed description of the surface deposits of North-eastern Iowa, with references to observations of a similar nature in other localities, and some general conclusions, was read by the author before the American Association at its St. Louis meeting, and is printed in the Proceedings for 1878. Since the preparation of that paper additional observations have been made in the same region; and some other localities, mainly in the State of Illinois, have been visited. A general section has been made across the northern portion of this State, from the Mississippi on the west to Lake Michigan on this east, at about 42° N. lat. A like section has been made the greater part of the length of the State from north to south, at about long. 89° W. from Greenwich. The data employed in the construction of these sections were chiefly derived from personal observations on the surface, in channels of erosion, and in artificial excavations on the surface, in channels of erosion, and in artificial excavations; but use has also been made of observations of other persons, collected by means of extensive inquiries from, and correspondence with, local geologists and others. In Iowa a formation, believed to be distinct from any previously described, has been discovered, and a rather anomalous distribution of the member considered to be the equivalent of the loess has been brought to light. Several åsar, which seem to be homologous with those of Scandinavia, have also been traced over some distance.