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cannot be urged in support of its eolion origin on this side of the Atlantic. Where the loess of the United States is typically developed, and has any considerably thickness, its iron content is not often thoroughly oxidized below a depth of four to six feet. The same is true of the loess of some parts of Germany. So, too, it may be much more troublesome to account for the presence of even a few aquatic shells in an eolian deposit. The frequent inter-stratification of loess and sand at the base of the formation, the occasional presence in the loess of stone quite beyond the power of wind to transport, its general habit of following river courses, the presence of aquatic shells, and its lack of oxidation and leeching except for a short distance from the surface, are considerations of sufficient weight to make it very doubtful if the larger part of the American loess can be due to the wind. On the other hand, we believe that some (quantitatively a small part) of the loess of the United States is unquestionably of eolian origin. It has long seemed possible to the writer that formations may have been grouped together under this name which have had very different origins at very different times. This notion is emphasized in the volume before us, where the adobe of the United States, two or three thousand feet thick, is referred to as the loess, though this is not the formation commonly known as loess, and can hardly be one with it in origin. Many new facts are given concerning glaciation in regions where the work of the ice has not, until recently, been known.

The incorporation of the great body of new facts and suggestions throughout the volume has meant the digestion of a large body of recent literature. Indeed, there appears to have been very little geological literature produced since the earlier edition of the work of which the author has not made use, and to which we do not find explicit reference in the new edition.

The difficulty of finding satisfactory summaries of the physical features of European countries makes such essays as the above especially welcome to the American student, particularly if he contemplates a trip abroad. The essay is one of a series of lectures, published by