Intimately connected with the subjects treated of in the last chapter, is the nature, origin, and age of certain loamy deposits, commonly called loess, which form a marked feature in the superficial deposits of the basins of the Rhine, Danube, and some other large rivers draining the Alps, and which extend down the Rhine into the Low Countries, and were once perhaps continuous with others of like composition in the north of France. [35] It has been reported of late years that human remains have been detected at several points in the loess of the Meuse around and below Maestricht. I have visited the localities referred to; but, before giving an account of them, it will be desirable to explain what is meant by the loess, a step the more necessary as a French geologist for whose knowledge and judgment I have great respect, tells me he has come to the conclusion that "the loess" is "a myth," having no real existence in a geological sense or as holding a definite place in the chronological series. No doubt it is true that in every country, and at all geological periods, rivers have been depositing fine loam on their inundated plains in the manner explained above in Chapter 3, where the Nile mud was spoken of. This mud of the plains of Egypt, according to Professor Bischoff's chemical analysis agrees closely in composition with the loess of the Rhine.* (* "Chemical and Physical Geology" volume 1 page 132.) I have also shown when speaking of the fossil man of Natchez, how identical in mineral character and in the genera of its terrestrial and amphibious shells is the ancient fluviatile loam of the Mississippi with the loess of the Rhine. But granting that loam presenting the same aspect has originated at different times and in distinct hydrographical basins, it is nevertheless true that during the glacial period the Alps were a great centre of dispersion, not only of erratics, as we have seen in the last chapter, and of gravel which was carried farther than the erratics, but also of very fine mud which was transported to still greater distances and in greater volume down the principal river-courses between the mountains and the sea. MUD PRODUCED BY GLACIERS.