380 



THE BEAUTIES OF NATURE 



them even as much as 78 — miles. Many 

 also have central cunes, closely resembling 

 those in our own volcanic regions. In some 

 cases the craters are fillecl nearly to the brim 

 v^rith 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 an}' 

 change in a lunar mountain. 



The Moon, being so much smaller than the 

 earth, cooled, of course, nuich more rapidly, 

 and it is probal)le that these mountains are 

 millions of years old — much older than many 



