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Probably you never heard of rillensteine. Neither had the staff of the Desert Magazine until this story came in from a professor at Pomona college. But now we know the answer—it is a piece of limestone that looks as if the worms had been eating it. As a gem stone, it doesn't rate high—but no selfrespecting rock garden should be without a rillensteine specimen—all covered with wurmrillen. Rainwater carved the unusual pattern on this specimen of rillensteine from Silver mountain. ike 7
Rillensteine outcrop on the Mojave desert near Adelanto. several such localities. The first was a veritable outdoor museum of rillensteine. This locality is just east of Garnet station, California, on the Southern Pacific railroad. It is called Garnet hill, and is an isolated hump of no particular dignity, at the east end of San Gorgonio pass. Unfortunately, this occurrence is in definitely hostile territory where collecting is a grab-and-run proposition. Although there are thousands of tons of rilled limestone scattered around over the hill, rumor has it that a party of famous geologists was once chased off the premises in absolute disorder by an irate woman. She was armed with a pickhandle. I was not on that expedition and can only speak from hearsay, but a reliable informant says it was one of the most laughable episodes in geologic history. Recently, one of the leading participants in the Garnet Hill debacle told me the locality is now safe for collecting and no hostile demonstrations need be expected. I secured several specimens of the rilled limestone there without any unpleasant results. These were taken to the laboratory and "given the works" under the microscope, followed by a complete chemical analysis. I gained much information. For one thing, I found frequent flakes of mica and graphite extending into the channels. Mica and graphite are two very soft minerals and any wind action would certainly have cut off these flimsy minerals if it had been strong enough to wear away the hard limestone itself. After several other observations, including a stiff third degree by means of a synthetic "dust-devil" set up in the laboratory, the wind was finally cleared of all suspicion. The action of the sand or dust blast was found to merely smooth away the surface, and had no tendency to produce anything even remotely resembling "wurmrillen." I now felt certain that I was on the trail of the alternative suspect by the name of "solution." This phase of the work took three of us into the Mojave desert at Silver mountain. Silver mountain is the high sounding local name of an unimportant peak in the Shadow mountains nctthwest of Adelanto. To reach this point take plenty of water and bedding and follow the map. Be prepared to make a two day trip of it and camp out. Anyway, it will be more fun that way. When I was there, Silver mountain was a happy hunting ground for rillensteine during the day but a place of near arctic temperature. It was in January. The expedition was sleeping on the ground and the only available firewood was the dead trunks of Joshua trees. These give a lot of heat at the start but burn as fast as a pile of lace curtains. At Adelanto we really pinned the goods on "solution." It was an open and shut case. On many of the outcrops, the rills ran down on both sides like water from the ridge of a house. Thin and less sharp at the top, they became deeply channeled at the ground-line. Beneath the soil we found a continuous deposit of caliche or soft and chalky limestone. This type is always formed by the rapid deposit of calcium carbonate from solution. The next stage of our operation was to find how and why solution had formed wurmrillen. We obtained this information from two other sources—at Black mountain, about 15 miles northeast of Victorville and in the laboratory. At Black mountain the entire faces of enormous buttes are rilled and channeled in the most remarkable way. Fossil coral in these specimens make rocks from this locality doubly interesting. Here, the true wurmrillen only occur where the run-off is most rapid. At the bottom of the buttes where the water has had time to accumulate for a considerable time, strong V-shaped grooves surround fossil coral embedded in the limestone. The rills were definitely the work of water—but how? Ordinary water, free from any trace of acid is a very poor solvent for limestone. In fact, one litter (about a quart) will dissolve only 14 milligrams (about the weight of a fat fly) of limestone at 18 degrees. But, when the water contains much carbon dioxide in solution, which Block of rillensteine from Garnet hill in Coachella valley, California. DECEMBER, 1940 11
Page 1 and 2: AM-: ^ Jff* .a. DECEMBER, 1940 M "A
Page 3 and 4: DESERT NOV. 29-30—Fiesta Days in
Page 5 and 6: Two white men found the lost silver
Page 7 and 8: who claimed that section as his pri
Page 9: By GENE O. PARKS Las Vegas, Nevada
Page 13 and 14: In Arizona everybody knows Reg Mann
Page 15 and 16: living room of his home. He must ha
Page 17 and 18: The Gap, described in this story, i
Page 19 and 20: ly, because they were compelled to,
Page 21 and 22: Chuckawalla mountains in the Southe
Page 23 and 24: menced to fall. We had visions of s
Page 25 and 26: This picture was taken from the oas
Page 27 and 28: work would restore the idyllic litt
Page 29 and 30: Hard Rock Shorty of Death Valley .
Page 31 and 32: they appear in their native environ
Page 33 and 34: and release its surplus waters duri
Page 35 and 36: Palmdale . . . Rexford Johnson, cur
Page 37 and 38: Winter is approaching at Yaquitepec
Page 39 and 40: Cjemb and This department of the De
Page 41 and 42: December—Turquoise Turquoise, the
Page 43 and 44: Min&i and Bisbee, Arizona . . . Mor
Page 45 and 46: Ancient Ruins in New Mexico! Who ca
Page 47 and 48: Bring the Mystery and Enchantment o

M "A G A Z I N E AM-: - Desert Magazine of the Southwest

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