502 Sir H. H. Hoicovth — Ile2)Iy to 3Ir. Juices- Brou-ne. 



drainage, and river valleys. The surface of the planet is literally 

 covered with unearthly circular formations, from 10 to 100 or even 

 150 miles in diameter, enclosing level plains sunk from 1000 to 

 10,000 feet beneath the outer surface, and bordered by vast ramparts, 

 having about the same cubic measurement as that of the excavation. 



4. The mountains, peaks, and cliffs are white, and ivhifest where 

 they are steepest. The darker parts of the surface are levels, as 

 though due to accumulation of meteoric dust thereon. 



5. There is an entire absence of raised level floors like those in 

 terrestrial volcanoes, and there is no perceptible difference whatever 

 between the polar and equatorial surfacing ; if the large and small 

 circular formations about the equator have been volcanoes, then 

 have the lunar poles been finally surfaced in the same way. 



Lastly, if, as is now generally aduiitted, the moon formerly 

 rotated more rapidly on her axis, and has been slowed down by 

 tidal friction, this would imply a temperate era, the existence of 

 water, and of erosive action, which would have effectually scoured 

 off all the so-called "volcanic" details now visible everywhere. 



So far our moon, though so admirably suited in some ways for 

 study by geologists, seems to have received rather scant attention. 

 Professor Judd, in his most instructive work on Volcanoes, p. 305, 

 says "the moon appears to be destitute of both atmosphere and 

 water. Under these circumstances we find its surface, as we might 

 expect, to be composed of rocks which appear to be entirely of 

 igneous origin; the mountain-masses, unworn by rain or frost, river 

 or glacier, being of most prodigious dimensions as compared with, 

 those of our own globe, while no feature at all resembling valleys, or 

 plains, or alluvial flats are anywhere to be discerned upon the lunar 

 surface." 



The whole of Prof. Judd's work, however, is such a clear and 

 beautiful demonstration, that without water there can be no volcano, 

 that I feel sure he will excuse my pointing out the above difficulty. 



With your permission I wouhl like to say that if any reader 

 desires to study my "Theory of Lunar Surfacing by Glaciation," it 

 is to be had at Messrs. Thacker & Co.'s, 87, Newgate Street. I 

 earnestly hope that some of your geological experts will take this 

 matter in hand ; it will certainly repay them, and perhaps enable 

 selenology to make some advance, after prolonged stagnation. 

 SiBSAGAR, Assam, 11th June, 1892. 



YIL — The Mammoth and the Glacial Drift. A Eeplt to Mr. 



A. J. Jukes-Browne. 



By Sir Henry H. Howorth, K.C.S.I., M.P., F.G.S., etc. 



IN a letter in the last Number of the Geological Magazinf, 

 Mr. Jukes-Browne takes me to task, with some asperity of 

 language, for my views on the true horizon of the Mammoth, 

 You will, I am sure, allow me to reply to him. He speaks of my 

 " looking down from some literary height upon practical geologists 

 in the plain," and goes on to say that I have " no practical 

 experience as a geologist, and bids me study the facts in the field." 



