358 



AMERICAN FORESTRY 



FISHER'S PEAK AS SEEN FROM NEAR TRINIDAD, COLO. ; A PART OF THE RATON MESA 

 STANDING 3,500 FEET ABOVE THE POINT OF OBSERVATION. 



level of the mesa and Red Mountain is 

 considerably higher. These elevations 

 have the conical form of volcanoes, 

 but if they ever possessed craters all 

 evidences of them have been destroyed. 



The older and more extensive sheets 

 of lava are supposed to be products of 

 fissure eruption. The molten rock 

 welled up through great cracks in which 

 the lava finally solidified, giving rise to 

 the dikes now exposed in the eroded 

 areas surrounding the mesas. In some 

 places also the lava was extruded 

 through relatively small pipes. In these 

 pipes the lava consolidated and inas- 

 much as it is harder than the rocks 

 through which it found passage, it has 

 not been eroded so fast as the soft 

 rock surrounding it, and the solidified 

 filling of the pipes now protrude from 

 the surface as "plugs" such as Water- 

 vale Butte. 



After the first group of lava flows 

 had been formed, there seems to have 



been a cessation of volcanic activity 

 and the lavas were attacked by ero- 

 sion. The sheets were cut through 

 and great quantities of them, as well as 

 of the older rocks, were eroded away. 

 Then the dormant forces became ac- 

 tive again and other lava sheets were 

 formed in the degraded areas below 

 the older sheets. The younger lavas, 

 at least in part, issued from volcanic 

 vents and the volcanoes formed about 

 these vents still remain, but in their 

 turn these lavas were attacked by ero- 

 sion and deeply dissected before still 

 later eruptions occurred, resulting in 

 the recent flows and in such perfect 

 cinder cones as Mount Capulin and 

 others illustrated in this paper, a dozen 

 or more of which were formed. 



There were three well-marked peri- 

 ods of volcanism in this region sep- 

 arated by long periods of time and 

 doubtless numerous less well-marked 



