354 E. E. Eoicorth—The Loess. 



connection with the so-called geyser deposits of the American 

 geologists. Speaking of the Pliocene beds of Nebraska, he says, 

 " Near or in many of these beds all over the Pliocene region of the 

 plains are found many extinct geyser tubes, and sometimes old 

 geyser basins. Of these I observed at least thirty betw^eeu Arapahoe 

 and the west line of the State ; I have also found them in the Loup 

 region, and on the Niobrara. As some of these geyser tubes had 

 their exit in the Fort Pierre group on the Upper Republican, it is 

 probable that they commenced their work in the Cretaceous period, 

 and were in operation all through the long centuries of the Eocene, 

 Miocene and Pliocene periods, and far into the Quaternary ; a similar 

 bed exists on Oak Creek, which was deposited in interglacial times. 

 Nebraska and Northern Kansas, in fact, was a great gej'ser region 

 all through the Tertiary period. It far exceeded in the number and 

 magnitude of its geysers the Upper Yellowstone region and Iceland 

 at the present day. Few memorials of these old extinct geysers are 

 visible at the present time, owing to their being covered up by 

 the superincumbent Quaternary deposits, but enough remains to 

 show that a prodigious number must have existed at least in Pliocene 

 times " (Sketches of the Physical Geography, etc., of Nebraska, 

 pp. 239 and 240). If we examine the analyses that are available of 

 the Loess from different districts of the silico-alkaline earths that 

 characterize the Nebraska Pliocene beds and of gej'serite proper, we 

 shall be constrained to assign them all three to the same ultimate 

 cause. This evidence is surely very irnportant, and it will, I trust, in 

 some measure affect Baron Richthofen's emphatic statement which I 

 have quoted. I showed in my paper that in the European area of 

 the Loess, calcareous springs, fumes of carbonic acid, and other traces 

 of still living volcanic action exist, while the pi'oofs that they 

 existed much more forcibly during the deposition of the Loess are 

 very familial*, the intercalation of Loess and volcanic ashes in the 

 Rhine volcanoes being the most forcible. This I have already 

 shown at some length in a previous paper. In regard to the 

 mountains of North China, which are the focus of the Loess deposits 

 there, I might quote many additional facts from Pere David's papers 

 already cited, in which he has shown how in all directions these 

 mountains are strewn with evidences of volcanic forces actively at 

 work down to the most recent geological period, and apparently 

 showing special signs of activity in the Quaternary period. 



It will be remembered that in postulating a subterranean origin 

 for certain ingredients of the Loess, I did so in a very hesitating way, 

 and merelj'^ as a tentative hypothesis. Tentative hypothesis only it 

 still remains, as does every opinion I hold ujjon every subject ; to 

 be surrendered immediately, and without regret, directly it is shown 

 to be inconsistent with the facts. At present, however, so far as my 

 judgment goes, it is the only hypothesis available, for the only 

 process that I know by which siliceous mud consisting of very 

 comminuted angular particles entirely free from structure, and from 

 the presence of foraminifera, etc., charged with carbonates, and 

 like the Loess in every respect, can be explained, is the theory I have 



