858 THE JOURNAL OF GEOLOGl. 



The adoption of any general terminology for the pre-Cambrian 

 rocks is deprecated. In the author's judgment, " the term Laurentian 

 cannot henceforth have more than a local significance." He further 

 indicates his belief that "there will be much less impediment to the 

 progress of investigation by the multiplication of local names than by 

 the attempt to force indentifications for which there is no satisfactory 

 basis. Each country will have its own terminology for pre-Cambrian 

 formations, until some way is discovered of correlating these formations 

 in different parts of the globe." The great duration of the time inter- 

 val represented by the pre-Cambrian sedimentaries and their great un- 

 conformities is distinctly recognized. Much fuller details are given in 

 this than in any earlier edition, concerning the development of the 

 pre-Cambrian in different parts of the world. On the whole, the 

 chapter on pre-Cambrian is much more satisfactory than in any other 

 existing text-book. Several other periods are much more fully dealt 

 with in this edition. This is especially true of the Silurian and Ter- 

 tiary. Various new figures of fossils are introduced, representing 

 important species of recent discovery. 



In the section dealing with glacial geology, we notice that no dis- 

 tinction is made between the formations known in America as kames and 

 osars, and are a little surprised to find the statement concerning kames 

 (osars as we know them in America) that "no very satisfactory statement 

 of their mode of origin has yet been given." Perhaps this may be true 

 in a restricted sense, since there is much discussion as to the exact 

 character of the streams which produce them, but that the formations 

 which we have come to call osars were produced chiefly by superglacial 

 or subglacial streams, does not seem to admit of serious question, so 

 far as America is concerned. We are also surprised to find the loess 

 placed in the recent or post-glacial series. This is not the correct 

 reference of most of the loess in the United States, for at various points 

 along the northern border of the very extensive loess covered area, as 

 in Illinois and Iowa, the loess is frequently found beneath the till of 

 the later ice invasions. The eolian theory of the origin of the loess is 

 favored. This seems to be by far the most satisfactory theory for the 

 Asiatic loess, and is finding much favor in connection with the loess of 

 Europe. It is doubtless the loess of these countries to which reference 

 is especially made. But the points urged in support of the eolian 

 theory are not all applicable to the American formation. For example, 

 "the thoroughly oxidized condition" of the iron content of the loess 



