File:American forestry (1910-1923) (18144154695).jpg

Title: American forestry
Identifier: americanforestry181912amer (find matches)
Year: 1910-1923 (1910s)
Authors: American Forestry Association
Subjects: Forests and forestry
Publisher: Washington, D. C. : American Forestry Association
Contributing Library: The LuEsther T Mertz Library, the New York Botanical Garden
Digitizing Sponsor: The LuEsther T Mertz Library, the New York Botanical Garden

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358 AMERICAN FORESTRY
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FISHER'S PEAK AS SEEN FROM NEAR TRINIDAD, COEO.; 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

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