THE STONE FOREST OF FLORISSANT. 



481 



that produced the lake's annihilation, but in the main the aerial 

 discharges of volcanoes. Even to-day the practiced eye will soon 

 pick out from among the many mountain forms that surround 

 this ranchland the conical contours of the volcano. A few such 

 stand by themselves, neither of great height nor of imposing 

 mass ; others are disposed in linear series, much like the cones 

 which so abundantly scatter themselves over the southwestern 

 and Mexican plateaus. We ascended one of these, a conelet of 

 perhaps one hundred and fifty feet elevation, whose partially 

 wooded sides were yet the ancient slag and cinders, and from 

 whose top projected the plug of lava which marked the position 

 of the former vent. In a pit near by could be seen the hard 



The Giant Stone Fuue.-i 



l) ijf 1*'i.ijkissant. Forty-five feet in circumference. 



basalt-trachyte which forms the existing core of the mountain — 

 the material which in early Miocene times, or perhaps still earlier, 

 was active in the distribution of the loose rock fragments which 

 everywhere lie scattered about. In the days of its activity the 

 foot of the volcano bordered a still more ancient lake, or was even 

 immersed in it, as the lacustrine deposits which largely encircle 

 it plainly show. In these are found in scattered spots a number 

 of fresh- water types of mollusks — Planorhis, Physa, Limnea, Val- 

 vata, Cydas — their shells as beautifully preserved as the much 

 more delicate parts of the insects which were shortly added to 

 them. 



The eruption came, and with it clouds of ash sailed upward, 

 only to fall back into the lake waters, and with them form a 

 sticky and lasting paste, ultimately to harden into a compact 



