EXTINCT VOLCANOES OF NORTHEAST NEW MEXICO 359 



CAPUUN MOUNTAIN, AN EXTINCT VOLCANO OF RECENT ORIGIN, NEAR FOLSOM, N. M., 

 AS SEEN FROM THE TOP OF A NEIGHBORING VOLCANIC PEAK FIVE MILES AWAY. 

 THE CINDER CONE RISES NEARLY 1,500 FEET ABOVE THE PLAIN. 



periods will be recognized when the 

 region is studied in detail. Three peri- 

 ods are well illustrated in the canyon of 

 the Dry Cimarron, where the rim of the 

 canyon consists of lava belonging to one 

 of the ancient sheets. Thi = sheet was 

 eroded and the canyon cut down nearly 

 to its present depth when a flood of 

 lava was poured into it probably from 

 the crater of Mount Emery, an extinct 

 volcano standing about a mile south 

 of the Cimarron. The sheet thus 

 formed within the canyon was later 

 partly eroded away. The bed of the 

 canyon was lowered slightly below its 

 present level when a great stream of 

 lava, presumably from Capulin, flowed 

 down the canyon for a distance of 

 about 27 miles filling the stream bed 

 and overflowing it in some places, 

 spreading to the confining walls of the 

 canyon. The surface of this youngest 

 lava constitutes the present floor of the 

 canyon. 



Just as there are three conspicuous 

 and well-defined periods of lava flow 

 in this region, so are there three dis- 

 tinct groups of extinct volcanoes which 

 correspond in time, in a general way, 

 to the lava flows. The oldest is repre- 

 sented by Sierra Grande which is the 

 only one of this group known to the 

 writer; the second, by Robinson, 

 Emery, and half a dozen unnamed 

 peaks ; and the youngest group by Cap- 

 ulin, the Horseshoe, and a large but 

 undetermined number of volcanic cones 

 of recent origin. 



THE SIERRA f.RANDE 



Sierra Grande forms one of the 

 most conspicuous geographic features 

 of the volcanic region of northeastern 

 New Mexico. It is a conical mountain 

 of volcanic origin, about 10 miles south 

 of Folsom, New Mexico, standing 



