Elk, grouse, blacktail deer, antelope, rattlesnakes, prairie dogs, skunks, badgers, owls, whistling martens, wild sheep, and the grizzlies we never saw alive were all part of the great West. So were the bucking cayuses and kicking mules with which we lived, numerous ranchers, prospectors, soldiers, sportsmen, and guides. Once we were joined by a sheriff looking for an escaped desperado from Red Lodge Prison.
Just before I left the Yellowstone, I visited the hot springs and geysers. With more than 4,000 vents, the geyser basins are steaming areas in the forest. At Mammoth, the carbonate terraces show exquisite ripples and sculptured cups in steps. One hotter group of waters, through the igneous lavas and granites, becomes full of silica and deposits sinter. The other, through limestones, deposits travertine. The alkaline siliceous waters deposit such strong silica edifices as to hold the explosive steam boilers of the geysers. Both silica and lime deposits are led to gorgeous sculpturing and to brilliant colors at their borders caused by the blue-green algae, which live at temperatures up to 150° Fahrenheit.
The boiling waters have been superheated volcanically since Tertiary volcano times, when first dark magnesian, and afterwards siliceous, lavas were ejected. Here is the same order Daly and I found in Vermont; the dark rocks first, rifting through slate, the granites last, with quartz cutting the dark rocks. The cavities among the Yellowstone geysers show quartz.
The surprise to me was that the geyser basins were eternally breaking down, cracking, dissolving, making new geysers in the forest. Instead of being chiefly deposition, the hot spring action is chiefly erosion. It is a vast cycle of hot magma gases and rainwaters from Tertiary times to now; from 20 million years ago to now. A long time.
Remember that the last retreat of the glacier-period ice was only 20,000 years ago. That ice found the geyser basins in full swing. A thousand times farther back were the Yellowstone volcanoes in full activity, and they kept going while the continent lifted and pushed the Gulf of Mexico from the Great Plains to where it is now. And yet that 20 million years was only a twenty-fifth of the time back to the trilobites, and a Yellowstone seabottom bed of that age is under all the lavas. Our schoolbook history is pretty small.
In all directions the ground of Norris Geyser Basin is cracking and changing. The geysers are utterly unreliable, here today and mere hot springs or empty cracks tomorrow. Old Faithful intervals range from thirty-eight to eighty-one minutes, quite irregular. The New Crater was a squirting, scalding jet which killed the trees and vegetation all about. Its seemingly regular, twenty-five foot jets shot up at forty-five degrees inclination about every three minutes. Later, in 1922, I was to find this geyser totally different. Careful studies have shown that water of this elevation boils at 199° Fahrenheit; one geyser gave off 253° Fahrenheit, or fifty-four degrees of superheat, seventy-two feet down its shaft. This is the only place of superheated waters known on earth. The roaring steam of the Black Growler has eighty-one degrees of superheat. The quantity of carbon, sulfur, and chlorine in the waters is so excessive, though it is very small in the rock, that a source of heat from volcanic gas is certain.
The net result is thousands of boiling springs of rainwater, soaking a sponge of rhyolite rock over hundreds of square miles, erupting over a remnant volcanic furnace beneath, and eroding and dissolving out basins at the headwaters of the Mississippi.
Here is an object lesson in volcanic erosion. Here is a perpetual eruption of volcanic gases which has dwindled after millions of years of melting siliceous and carbonaceous rocks. It recrystallizes them as andesites, rhyolites, and obsidians, and mixes deep steam with rainwater to do the work of erosion and water solution and of deposits, over a vent at the heart of the Rocky Mountains. As usual, this vent has cluttered itself from age to age with the melt of the deep earth crust, namely basalt, which Yellowstone’s lavas show repeatedly from bottom to top of its accumulations. And as usual, the vents themselves are hard to recognize, buried as they are under heapings.
In 1897 I returned to the Yellowstone, where I visited Death Gulch, a dismal solfataric gully with a trickle of cold, acid water near Cache Creek. Accompanied by Dr. F. P. King, I climbed up this gorge, where there was a bad smell and burning oppression of the lungs from hydrogen sulfide. It was a V-shaped trench 50 feet deep in volcanic puddingstones, whitened with alum and epsom salts. Bubbles rose through the water in many places.
The remains of eight big bears were found in the gorge, clustered in one place. The latest victim was a young grizzly with a clot of blood staining his nostrils from his last hemorrhage. Poison gas had killed him. Earlier visitors had found squirrels, hares, and butterflies and other insects killed by gas. Probably both sulfuretted hydrogen and carbonic acid gas do murder in still weather. However, we had the wind blowing up the gulch. We lit matches in hollows and carbon dioxide did not extinguish them. The same thing had happened when Mr. Weed in 1888 tested for carbon dioxide at Death Gulch.