E. H. Howorth — A Great Post- Cflacial Flood. 69 



excellent photographs of the Iowa stones, sixtj-seven in number, 

 which form the collections of Prof. Hinrichs, Mr. J. P. Irish, and 

 himself. They were taken by Mr. Thomas James, of Iowa city, and 

 are in the very best style of photographic art. 



Prof. Giimbel, of Munich, has recently published an interesting 

 paper on the characters of this meteorite. He finds the crust to 

 possess a deep bottle-green or brownish-red colour, and to possess 

 in polarized light all the characters of an amorphous glass-like mass. 

 When a fragment is heated, it turns of a dark-brown colour, like that 

 noticed by him in the eruptive rocks of the Fichtelgebirg, and he 

 regards this change as a safe indication of the presence of olivine. 

 The composition of the stone is found to be : — 



Meteoric iron 12-32 



TroUite 5-25 



Silicate, decomposed by acid 48"11 



Silicate, not acted upon by acid 34'32 



100-00 

 The silicate decomposed by acid is an olivine, having the formula 

 2 (I MgO, ^FeO), SiOgi and the insoluble silicate, which has been 

 regarded by Dr. Lawrence Smith as pyroxene, gave the oxygen 

 ratios — silicic acid = 29-68 ; bases = 10'29. It appears not im- 

 probable that in this case the silicate was not completely decomposed 

 during analysis. 



The paper is illustrated with an interesting plate of a microscopic 

 section, showing olivine, augite, meteoric iron, chroraite, troilite, 

 particles of a reddish hue which resemble garnet but which doubly 

 refract light and exhibit optical characters which will not allow of 

 their being identified with nosean, and chondra showing fibrous, 

 radiate, and granular structure, as well as others which evidently 

 consist of olivine, and some which are opaque and finely granular. 

 The meteoric iron has a hackly angular structure, and has the ap- 

 pearance which it would present if reduced to the metallic state in 

 the position which it at present occupies. 



(To be continued in our next Number.) 



y. — Traces of a Great Post-Glacial Flood. 

 I. The Evidence of the Loess. 

 {Concluded from p. 18.) 

 By H. H. Howorth, F.S.A. 

 "AYING examined the various theories of the origin of the Loess, 

 which have been current, and found them wanting, I would, 

 with great deference, propose another which has^not hitherto been 

 suggested by any geologist, and which offers at least a probable 

 solution of our untractable problem. In previous papers of this 

 series, if we have not proved, as we think we have, that the 

 evidence in favour of the Mammoth and his companions having 

 been suddenly overwhelmed by a great diluvial movement is 

 unanswerable, we claim to have at least shown a very strong 

 d 'priori probability in favour of such a view. If this view is correct, 



