1 882.] Geology and Paleontology. 92 1 



Howorth's, giving the evidence of the valley terraces in favor of 

 a great post-glacial flood ; and in the succeeding number Mr. 

 Howorth publishes a rejoinder to Baron Richthofen. He urges 

 that he, as well as Baron Richthofen, believes in the original 

 sub-aerial nature of the deposits, as proved by the animal and 

 vegetable remains, but that what is called the Loess is this old 

 land surface redistributed by the catastrophe which closed the 

 Mammoth period and formed the gap between Palaeolithic and 

 Neolithic man. He denies that the genera and most of the 

 species of mammals found in the Loess are such as now abound 

 in steppes, for the mammoth and the rhinoceros, the character- 

 istic quadrupeds, are forest animals; and he asserts that the 

 probabilities are that the lime-lined capillary tubes, which do not 

 occur at a greater depth than 45 feet, were formed by the percola- 

 lation of water. Wind-driven deposits would be sorted, the heavier 

 dropped first, whereas heavy grains occur throughout the Loess, 

 mixed with the lighter. Baron Richthofen asserts that the Loess- 

 covered portions of Europe must have had a steppe climate long 

 enough for the deposit to be formed, but if so, how could the 

 Helices and other damp-loving molluscs exist ? Whence did the 

 dust come to form this vast deposit? Wind blowing over grass 

 raises no dust. As, according to Baron Richthofen the steppes 

 of Mongolia are really Loess, and as the Loess is known to exist 

 in Russia, where can we possibly look for a dry area large enough 

 to supply this dust ? . 



Mr. S. V. Wood contributes an additional theory to this much 

 vexed question. In arctic climates where the soil is not covered 

 by ice, the surface would annually thaw and be converted into 

 mud by the melted snow. On all inclined surfaces it would slide 

 downward from the frozen soil below, and thus leave a lresn 

 surface exposed to the same agencies. Repeated depositions ot 

 this mud would fill the valley, and constitute the Loess. 



The Recent Discoveries of Fossil Footprints in Carson- 

 Nevada.— Monday evening, Aug. 28th, the California Acad, of 

 Scien. held a special meeting, with Vice-President Justin P. Moore 

 in the chair, to hear a carefully prepared paper on the Carson 

 Footprints," read by Joseph Le Conte, M.D., L.L.D Professor m 

 the Universityof California. He began by explaining that his atten- 

 tion was first attracted to the Carson prison stone quarry in 1808, 

 when he received from it the tooth of a species of the horse. On 

 June 20th, 1882, he first reached the quarry and savy the footprints 

 now uncovered/and found there the Committee of the Academy 

 diligently at work, with whom he, as only a member desired 

 most heartily to co6perate. He then described the locality as a 

 remnant of a sandstone elevation, which had been cut into by 

 erosion. An opening about 100 yards square had been quarried 

 into the ledge, which is surrounded on three sides by vertical, 

 cliffs from 10 to 32 feet high, on the floor of which the nearly 



