490 



THE GEOLOGIST. 



The fossils of the Lower Lias Clay are not very plentiful ; and the 

 course of this clay is much hidden by drift ; such shells as Rhynchonellce, 

 &c, are not, however, uncommon. 



CORRESPONDENCE. 

 THE LUNAR SEAS. 

 To the Editor of the Geologist. 



Sib, — When I commenced reading the first article in the last (the October) number 

 of the Geologist — namely, that headed, "What has become of the Lunar Seas?" 

 I expected to find that some attempt would be made in it to show that it was, at 

 least, probable that seas did formerly exist on the surface of our satellite ; and since 

 astronomers concur to tell us that the moon is destitute of water, I cannot but 

 think the expectation a reasonable one. But, reasonable or otherwise, it was 

 doomed to disappointment, as the existence of such seas is quietly assumed, not 

 only in the titular question but also throughout the paper. Thus we have (page 409), 

 " When we look up to the moon, what do we see? Great ocean cavities and no 

 water in them." (Page 410), " They do not tell us what has become of the water 

 that once v;as in them," i.e., the so-called Lunar Seas. (Page 412), "Then" (when 

 the moon was further from the earth) " it was it had its atmosphere and its ocean." 

 (Page 414), "Doubtless the moon had once ocean and air," and "One thing, 

 however, is certain, there are waterless ocean cavities on the moon." Now, I 

 confess I should like to have some reason for the belief that any of the " waterless" 

 cavities on the moon were ever " ocean cavities," or that at any time " the great 

 Oceanus Procdlarum was a rolling sea, and the Mare Serenitatis lay glittering 

 under the golden streaks of our earth's bright beams," before even speculating on 

 the question, "What has become of the Lunar Seas?" 



But waiving this point, and assuming that there were formerly "Lunar Seas," 

 on the simple grounds that, as Sir John Herschel tells us, 1 ' there are large regions 

 perfectly level, and apparently of a decided alluvial character in the moon."* Why 

 is it " of no use to say it is all gathered up on the other side" ? A statement of 

 the basis of this inutility would have been acceptable ; some reply to the reasoning 

 of Sir John Herschel on this point, for example. + Should we not be informed why 

 " we cannot believe that?'" Possibly, however, the basis of our alleged incredulity 

 is supposed to be contained in the next passage. "The moon alwaj 7 s presents one 

 side to our earth, and therefore her ocean waters ought to be drawn up on this, 

 and not the other side." Unfortunately, however, the fact stated will not carry 

 the inference placed upon it. Even if the moon had been a perfect sphere, with 

 its geometric centre coincident with its centre of gravity — which has been doubted — ■ 

 and having water distributed over its surface without any marked preference for 

 either hemisphere ; all other things being as now, the earth's attraction could not 

 draw, or have a tendency to draw, her ocean waters all up on the side always pre- 

 sented to the earth ; at most it could produce two oceanic protuberances diametri- 

 cally opposed, one on the point of her surface nearest the earth, and the other at 

 that most remote from it; in fine, two high water points, which, omitting the 

 Hhrations of the moon, would be stationary; since, in that case, the earth would 

 appear immovably fixed in the heavens, as seen from any point on the moon's 

 surface. Whilst, if the moon were so constructed that all her waters were gathered 

 up on that side always turned away from us, the attraction of the earth would only 



* "Outlines of Astonomy," 5th Edition, Par. 430. 

 t " Outlines," 5th Edition, Par. 436 a. 



