116 FROM NEBULA TO NEBULA 



northern half of the visible hemisphere where 

 the craters are fewest and the comparatively 

 featureless districts termed seas are found. 

 The finest range is that named after our Apen- 

 nines. It extends for about 450 miles and has 

 been estimated to contain 3000 peaks, one of 

 which Mount Huyghens attains the* altitude 

 of 18,000 feet. * * * Another considerable 

 range is the Alps situated between the Cau- 

 casus and the crater Plato. It contains 700 

 peaked mountains and is remarkable for its im- 

 mense valley 180 miles long and about 5 broad 

 that cuts it with seeming artificial straight- 

 ness and that, were it not for the flatness 

 of its bottom, might set one speculating upon 

 the probability of some extraneous body hav- 

 ing rushed by the moon at an enormous veloc- 

 ity, gouging the surface tangentially at this 

 point and cutting a channel through the im- 

 peding mass of mountains. * * * At first 

 thought it might appear that the great moun- 

 tain ranges were produced by bodily upthrust- 

 ings of the crust of the moon by some sub-sur- 

 face convulsions. But such an explanation 

 could hardly hold in relation to the isolated 

 peaks, for it is difficult if not impossible, to 

 conceive that these abrupt mountains, almost 

 resembling a sugarloaf in steepness, could have 

 been protruded en masse through a smooth 

 region of the crust. * * * We believe they 

 may be regarded as true mountains of exuda- 

 tion, produced by the comparatively gentle 

 oozing of lava from a small orifice and its 

 solidification around it; the vent, however, re- 

 maining open and the summit or discharging 



