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Francis Gerritt Wells

Publications and source records attributed to Francis Gerritt Wells.

11 recordsLinked to original sources
USGS1949

Chromite deposits near Seiad and McGuffy Creeks, Siskiyou County, California

The chromite deposits described in this report are in northcentral Siskiyou County, Calif. They are in two long tabular masses of peridotite which lie end to end and trend northnorthwest across the valley of the Klamath River. The Seiad Creek-Red Butte mass extends 10 miles north of the river and the Hamburg-McGuffy Creek mass 8 miles south. The outcrops of both are from 1 to 2 miles wide. The rocks that bound the peridotite on the east are thoroughly reconstructed schist and those bordering it to the west are less-metamorphosed volcanic and sedimentary rocks. The schists have been considered to be pre-Cambrian age, whereas the rocks to the west are probably of early Triassic age. Strictly speaking, the chromite-bearing masses are complex bodies of ultramafic rock consisting mainly of dunite but also containing saxonite, lherzolite, pyroxeni,te and hornblendite (listed in order of abundance). Only the dunite contains chromite ore. The tabular peridotite masses lie parallel to planar structures in the older rocks, but in their internal make-up no large- scale structural pattern has been recognized. The most con- spicuous internal structure is the linear arrangement of the chromite-rich schlieren in the ore-bearing parts of the peri- dotite. A typical ore body may include parts made up of evenly disseminated chromite; the richest and largest bodies, however, are made up of concentrated, closely spaced chromite schlieren of different size, shape, and richness. Some schlieren contain 80 to 95 percent of chromite, but most of them contain 25 percent or less, and the ore must be concentrated to yield a marketable product. Chromite is composed of chromic oxide, alumina, ferric oxide, ferrous oxide, and magnesia in different proportions. Hence the ~bromic-oxide content of pure chromites differ. It is consistently high for the chromite from this area as it ranges from 55 to 58 percent. The iron content is likewise consistently high, ranging from 14 to 21 percent. The total reserves of indicated and inferred ore as of May 1945 were 274,500 short tons, which would average 8 percent Cr 2 O 3 . The Seiad Creek mine (Mountain View group) contained the largest deposit; reserves amounted to 212,000 short tons. The McGuffy Creek mine contained 50,000 short tons of indicated and inferred ore. Four other deposits, the Emma Bell, Kangaroo, Mountain, Fairview, and Ladd, contain a few thousand tons of ore each.

California↗
USGS1938

The origin of the iron ore deposits in the Bull Valley and Iron Springs districts, Utah

A summary of the geology of the Bull Valley district, southwestern Utah, and a description of the occurrence of the magnetite and hematite deposits is given, as well as brief descriptions of the ore pits at Iron Mountain and Desert Mound 20 miles to the northeast, in which deposits formed under similar geologic conditions have been developed. Neither the ores nor the country rock show the features characteristic of contact-metamorphic deposits. The following explanation of the origin of the deposits is offered. During the intrusion of monzonite porphyry stocks, the hoods and overlying rock were fractured, causing a sudden release of pressure and liberating FeCl 3 and H 2 O gas from the stocks which were still at high temperature. These gases found ready egress to the surface along tension fissures without appreciably heating the country rock. They deposited magnetite and hematite in the fissures and replaced the contiguous fractured limestone. The period of gas emanation was brief and the hydrothermal stage probably evolved during the later magmatic history never reached this area. The deposits were formed under a cover of less than 5,000 feet.

Utah↗
USGS1937

Recent geologic studies on Long Island with respect to ground-water supplies

Recent studies have shown that relatively impermeable clay beds are widespread on Long Island but that erosion channels cutting through them permit restricted recharge of the underlying beds in some parts of the island. Of the more than 200,000,000 gallons of water a day now pumped from wells, about 65 per cent. comes from the surficial beds of Illinoian or Wisconsin age. Because of the restricted recharge of the lower beds and the desirability of saving these beds for use in localities where the upper beds may more easily be contaminated by salt water, any future large developments of ground water should be drawn from the surficial beds.

New York↗