Cover: Columnar rhyolite in the Balanced Rock area.
CHIRICAHUA
NATIONAL MONUMENT
Weirdly beautiful pinnacles and columns eroded in volcanic rocks high in a forested range, which forms a mountain island in a desert sea.
The National Park System, of which this area is a unit, is dedicated to conserving thescenic, scientific, and historic heritage of the United States for the benefit and enjoymentof its people.
Unbelievably tall and slender pinnacles,startling likenesses of giant beasts and men,grotesque and weird figures such as mightinhabit another world—all these and manymore, carved by Nature in volcanic rock,are crowded into 17 spectacular squaremiles of ridge and canyon on the westflank of the Chiricahua Mountains.
Rising steeply from the grasslands ofsoutheastern Arizona and southwestern NewMexico, the Chiricahuas present a verdant,forested island in a brown sea of desert.Many varieties of trees, shrubs, and floweringherbs clothe steep canyon walls. Shadyglens, alive with birds, are frowned uponby rows of strange massive spires, turrets,and battlements in this fascinating wonderlandof rocks.
Geological Story
What geological forces created these strikingand peculiar pinnacles and balancedrocks? Geologists explain that millions ofyears ago volcanic activity was extensivethroughout this region. A series of explosiveeruptions covered the level area withlayers of volcanic rock fragments. Manyyears elapsed between such periods of activity,resulting in a series of blankets, layerupon layer. Since the eruptions varied inmagnitude, the resulting deposits were ofdifferent thickness.
Finally, the eruptions ceased, and werefollowed by movements in the earth’s crustwhich slowly lifted and tilted great rockmasses to form mountains. The stressesresponsible for the movements caused a definitepattern of vertical cracks. Storms andother agencies of erosion, especially runningwater carrying small particles of rock, immediatelyset to work on the long, slow taskof wearing down these mountains. Shallowcanyons became deeper and more rugged astime passed. Weathered rock formed soilwhich collected in pockets, and plant lifegained a foothold.
Where previous volcanic activity hadspread sheets of lava, the mountains werenow capped with layers of volcanic rock.Along the vertical cracks and lines of horizontalweakness, erosion began its persistentwork. Cracks were widened to form fissures;fissures grew to breaches. Undercuttingslowly took place. Gradually the lava masseswere cut by millions of erosional channelsinto blocks of a multitude of sizes and shapesto be further sculptured by the elements.
Erosion is still going on slowly and persistentlyamong the great pillared cliffs ofthe monument. Some of the most exposedportions have already been worn away.2Pedestal or balanced rocks have formed andfallen; others are tottering; more are justtaking shape. Within the span of a humanlife, only minor changes may be noticed, butwith the passage of the centuries the face ofNature is ever changing.
Although the spectacular erosional remnantsand the massive columnar structureof the cliffs will impress you even if youhurry through, you will see much more ofgeological interest if you can stop and usethe trail. Here and there are exposed bedsof volcanic ash and cind