380 



THE BEAUTIES OF NATURE 



CHAP. 



them even as much as 78 miles. Many 

 also have central cones, closely resembling 

 those in our own volcanic regions. In some 

 cases the craters are filled nearly to the brim 

 with lava. The volcanoes seem, however, to 

 be all extinct ; and there is not a single case 



Fig. 50. A group of Lunar Volcanoes. 



in which we have conclusive evidence of any 

 change in a lunar mountain. 



The Moon, being so much smaller than the 

 earth, cooled, of course, much more rapidly, 

 and it is probable that these mountains are 

 millions of years old much older than many 



