SAN DIEGO COUNTY.

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By W. H. Storms, Assistant in the Field.

There has been no marked development of mines in this county since the last report was issued, excepting in some of the districts of the Colorado Desert, of which mention will be made. The general geological and topographical features of this county have been so fully described in former reports that to repeat them here is unnecessary. At various times within the past two years new discoveries have been announced, and these have been developed to a greater or less extent, and in some instances, at least, with encouraging results.

HELVETIA MINE.

This mine is located a short distance from the town of Julian, and is equipped with a steam hoist and mill combined under one roof. The new shaft, which was started nearly three years ago, was sunk on the vein for 50 feet, at an angle of 75°, at which depth the shaft left the crevice and continued vertically to a depth of 225 feet. From this point a crosscut was started back toward the vein, running at an angle with its strike, the idea being to reach a pay shoot as quickly as possible. The shoot in question was the south extension of that developed in the old workings. The vein was encountered, and the drift continued along its course. At about 30 feet from the point of intersecting the vein in this drift of the shoot was found. It was hard, blue, rather glassy-looking quartz, filled with minute black particles, and showing considerable gold, some of the rock being very high grade.

The drift was continued along the vein, and finally reached a point over the level that had been run south from the old shaft, which is 300 feet deep. This new drift was found to be 14 feet higher than the old level. The mine was completely drained at the time of my visit, and a free circulation of pure air was found throughout the workings. The ground was ready for stoping, but owing to some legal difficulties arising the property was lying idle.

The appended sketch will give an idea of the present development of the Helvetia, which is one of the most promising properties in the district, and a type of the best class of mines of its kind found there.

The Helvetia, like other mines of the district, occurs in the crystalline schists, the quartz being found as lenses inclosed in the country rock. Some of the lenses might be mistaken for fissures, but I failed to see one possessing the characteristics of a “fissure.”

Nearly all the lenses exhibit a tendency to “make” into the hanging wall side of the country rock, the lenses of quartz following each other in a general direction, but at an angle with the stratification of the schists, and are separate and distinct from each other, being separated at the ends (where they sometimes overlap) by the “leaves,” as they may be termed, of the schistose country rock. These lenses were doubtless caused by a compressive stress on the schists, which had a tendency to split them, but was not powerful enough to cause an abrupt fracture. The accompanying sketch may convey an idea of the occurrence of these quartz lenses.

WORKINGS OF THE HELVETIA MINE NEAR JULIAN

LENTICULAR QUARTZ BODIES IN SCHISTOSE ROCK

By the above sketch it will be observed that there is a tendency on the part of the quartz lenses to follow a given direction, which lies at a small angle across the strike of the schists, and that these lenses are not connected, but occur independently, though all are the result of the same force which flexed and split the strata.

Other mines about Julian were idle at the time of my visit, the most of them being inaccessible, owing to water in the workings. Considerable money has been expended on the Owens Mine in an attempt to drain and recover the workings, but it was abandoned after several months of work and considerable expense.

More activity was exhibited in the mines about Banner than any other part of the district.

READY RELIEF MINE.

This is the largest and most extensively developed mine near Banner. It has earned considerable fame, not only as a producer, but for the peculiarities exhibited in the formation of its bunches of quartz, which contain disseminated grains and masses of pyrite.

The Ready Relief has several levels, all of which are connected by winzes and shafts. The huge bunches of quartz have, from their peculiar form, been denominated “rolls,” and I know of no better term which would convey a clear idea of their appearance. As a result of close observation made at numerous points in the mine and on the surface at the time of my visit, I formed the conclusion that the “rolls” of the Ready Relief Mine simply represent an exaggerated condition of the same sort of flexing of the schists that has produced the other mines of this district. The facts as observed lead me to the belief that the “rolls” or folds of the Ready Relief Mine, and its extensions, both north and south, are the result of a severe compressive stress upon the schists at right angle to a line running nearly northwest and southeast; that this force was exerted in the form of pressure and not of contraction; that as a result of this pressure there is a tendency exhibited on the part of the contorted strata to form a reverse fault and not a normal one, and that this power expended itself before the rocks were forced to yield to the strain to the extent of fracture, the result being an abrupt crumpling of the schists without disruption.

Along this line of disturbance percolating waters have deposited silica in enormous quantities. The schistose folded masses having been completely metamorphosed, massive quartz replacing the crushed and crumpled crystalline rocks, though the lines of its former schistose structure are in many places preserved.

A sketch of a characteristic section is here reproduced, and it may help the reader to form some conception of this unusual occurrence of gold-bearing quartz. The strike of the country rock is about northwest and southeast, and varies but little from this over a wide area. The rock is, generally speaking, a dark gray, rather close-grained, micaceous rock (argillite), having a dip to the east of about 80°. The succession of folds cut across the dip of the schists at an angle about 45° from the horizon.

It will be noticed that in places several of the rolls lie side by side. Where this occurs the pay shoot is very large. The thickness of the individual rolls varies from a few inches to 5 or 6 feet, and where the folds parallel each other a width of 12 to 20 feet or more is not uncommon. These rolls do not extend longitudinally a great distance, but seem to gradually diminish, being followed by others along the strike of the vein. It seems quite evident that had the stress which produced this folding or crumpling of the schists proceeded much farther an abrupt fracture must have resulted, and the Ready Relief vein would have been a fissure having a dip of about 45°.

At the time of my visit the Bailey Bros. were overhauling their mill of ten stamps and were putting in a 12-foot waterwheel of the Pelton style.

Though large amounts of quartz have been stoped from the Ready Relief there were still thousands of tons in the mine. Mr. Bailey informed the writer that the rock averaged about $15 per ton.

The other claims which occur along the same course as the Ready Relief are quite similar from a geological standpoint, though none of them exhibit the peculiarities of the folds in such a marked degree. Among the prominent mines on this belt are the Hubbard claims, which were being operated in the spring of 1892, the Redman, Antelope, Cincinnati Belle, and some others.

THE RUBY MINE.

This mine is located a short distance east of and parallel with the Ready Relief. It occurs at the contact of mica schist and syenite. A new five-stamp mill was in course of construction at the time of my visit, in which it was intended to crush quartz from the Ruby and Wilcox, an adjoining location. A small force was employed at the mine.

THE KENTUCK S.

Since the last report was published the Kentuck S came into prominence once more under the ownership of a St. Louis syndicate. A vigorous policy was inaugurated, and for a time all seemingly went well. The shoot of quartz, which had been opened to some depth, crops out along the flank of the steep mountain side. The vein pitches into the hill at a high angle. The manager selected a place to start a new vertical, three-compartment shaft at a point up the hill about 100 feet above the croppings. The shaft was started and was fully equipped. Massive timbers were placed in the most approved style. At a depth of 100 feet the work has reached the level of the croppings, and had cost, it is said, $10,000, and it was still about 125 feet down to a connection with the vein. Here the work was stopped, and has never since been resumed, standing an excellent example of how not to open a mine. The money expended in this shaft would have driven a crosscut tunnel from the base of the hill to the vein, giving at least 500 feet of backs, affording a cheap means of draining, ventilating, and exploiting the mine.

CINCINNATI BELLE.

Among the most promising properties I saw about Banner is the Cincinnati Belle, which has made quite a record as a producer of rock of high grade. This mine, together with several other claims, was purchased by a Pomona company in 1890, for the purpose of operating these mines, among them being the Gold King and Gold Queen Mines, of which mention will be made hereafter. The Cincinnati Belle is situated about 3,000 feet northwest from the town of Banner, and is in charge of D. C. Lane.

The shoots or lenses of quartz which constitute the so-called ore bodies of this mine occur in a general course along the strike of the schists, though each succeeding lens to the northeast “makes” into the hanging wall, as indicated in the cut under the head of Helvetia Mine.

The mine was developed by a tunnel of 168 feet in length, of which the first 40 feet required timbering. Near the mouth of the tunnel a shaft has been sunk on the pitch of the quartz lenses, to a depth of 200 feet. Levels were opened at intervals of 50 feet. The first level at the top had been cut 168 feet along the course of the lead; the second 68 feet; the third 120 feet; the fourth, fifth, and sixth each 50 feet. Each level exposed a bluish quartz rock, which returns in the mill from $18 to $40 per ton. It is free milling, and is treated by a simple amalgamation process.

Though this quartz contains some pyrite, which is auriferous, carrying $8 to $10 per ton, no attempt is made to save the sulphide. The mine makes but little water, and all the quartz and waste are hoisted in a bucket. Pine timber is used, which grows in the neighboring mountains above the mine. It costs 11 cents per running foot at the mine. The property was only under process of development at the time of my examination, and as but little stoping has been done, the cost of mining per ton could not be arrived at. The lenses vary greatly in size, ranging from a few inches to 4 feet. The vein or mineral-bearing zone is accompanied by a fissure, which runs along nearly parallel with the quartz at a distance of a few feet on the hanging wall side. This fault has resulted in the crushing of the country rock along its course.

In this vein, as it may be called, the rock has been completely changed, clay, talcose, and chloritic mineral replacing the micaceous rock. This mineral contains some gold. The inclined shaft has two compartments and is substantially timbered throughout. From the mine the company has graded, along the mountain side, 4,000 feet of road, over which the quartz is transported to the mill in the town of Banner at an expense of 75 cents per ton. The mill contains ten stamps.

The mill is quite complete, but poor judgment was shown in the arrangement by the management under whose supervision it was built, which was before the present Superintendent was in charge. As an instance, the rock from the mine when delivered at the mill is dumped into an ore bin outside the mill. The rock is then taken inside as required and dumped on a grizzly. As usual the large pieces fall on the crusher floor, where they are fed by hand into the jaw rock-breaker, which stands above the level of the floor. This sort of management necessitates extra and unnecessary work.

THE GOLD KING AND GOLD QUEEN MINES

Are located about 4 miles west from Banner, and are owned by the Pomona company, that owns the Cincinnati Belle. Only four men were employed in these mines at the time of my visit, prospecting work only being done. The quartz raised from these workings is hauled 11 miles by road to Banner. The quartz is high grade, and pays well, but no large amount was developed.

THE STONEWALL MINE

Is located about 8 miles southwest from Banner on the Cuyamaca grant, belonging to the Waterman estate. The Superintendent, Waldo S. Waterman, informed the writer that nothing of special interest had been developed in the mine since the publication of the last report (1890).

MESA GRANDE DISTRICT.

A few miles to the northwest from Julian is located the Mesa Grande District, where lenses of a yellowish pellucid quartz of semi-granular texture have been developed somewhat. All of this quartz contains gold, and some of it is quite rich; but nothing of consequence has been done of late, further than to organize a stock company.

ESCONDIDO MINES.

Near the flourishing little town of Escondido are some old Mexican mines, which have been acquired by a San Diego company. The veins are gold-bearing, the quartz having formerly been worked in arrastras with evidently good results, as the surface workings are quite extensive. Within the past two years, however, little has been done on the property.

PINE VALLEY.

The Pine Valley Mines lie 6 miles from the Stonewall and San Diego Stage road, the nearest station being Descanso. Two mills, one of five and one of two stamps, crush the rock taken from the veins in the vicinity. This quartz, it was claimed, would mill over $50 per ton. The veins occur in a formation similar to that about Julian and Banner.

REPORTED TIN DISCOVERIES.

Frequently there have been rumors of the discovery of tin stone in San Diego County, but up to this time no such ores are known to exist outside of the property known as the Temescal Mines, which are located on the line of San Bernardino and San Diego Counties. However, in the large crystalline area which extends over a considerable portion of San Diego County, it would not be strange to find tin stone under conditions similar to those which obtain in the Harney Peak region in the Black Hills of Dakota. There the cassiterite is found in good-sized crystals and finely disseminated grains in a matrix of coarse-grained granite, which has been thrust up through the schists in the form of intrusive dikes of greater or less size. It usually is associated with tourmaline, wolfram, and other black minerals, making it difficult to distinguish it without making a test of some sort. The search for tin in San Diego County has been confined to looking for a black rock similar to that found in the Cajalco Mine.

DULZURA DISTRICT.

The Dulzura Mining District is 30 miles east and a little south of the city of San Diego, in a range of rather rugged mountains. Metamorphic rocks occur frequently, but masses of igneous rock have been intruded and constitute large hills throughout the district. Among these rocks are a light, greenish-gray feldspar porphyry, a dark-green, fine-grained diorite, a black aphanitic diorite, sometimes porphyritic, and a light cream-colored or greenish-white felsitic rock. In the immediate vicinity of Dulzura the latter rock occurs in the form of immense dikes striking northwest and southeast, crossing Cottonwood Creek to the south into Mexico. In one of these great dikes, which is several hundred feet in width, the mines of the district are found. They are principally chambered veins occurring on the line of a fault plane which has fractured the felsite, the hanging wall side of the slip going down, the movement causing the rock to become crushed and broken. Percolating waters have carried into the crushed mass mineral solutions, which have deposited the ores, chiefly iron sulphurets, where the most favorable conditions were found along the line of this fault plane. The subsequent oxidizing of the masses of ore thus formed has stained the rock a bright or dark red and sometimes yellow.

The rock contains gold ranging from a trace to $20 or over per ton. It was said the average was about $8. The oxidation of the ore bodies does not extend to any very great depth, the result being the occurrence of sulphuretted ores comparatively near the surface, though it was claimed by the mine owners that the sulphurets contained sufficient gold to make concentration and treatment by chlorination profitable. The mines are quite interesting from a geological point of view, and may, in time, prove equally so from a financial standpoint. No machinery had been built at the time of my visit. The felsite throughout the district, whenever observed, contained a considerable amount of pyrite, the surface rock nearly always presenting a highly mineralized appearance.

JAMUL CEMENT ROCKS.

The Jamul Portland Cement Mine and works are located on the Jamul rancho, 22 miles east of the city of San Diego. The company began the construction of expensive works in the spring of 1890, which were not completed until June, 1891, at a cost of $50,000. Seven kilns were constructed, together with large buildings. The capacity of the works is about 150 barrels a day. When in operation over forty men are employed at the mine and works.

The transportation problem proved a more serious one than had been anticipated, it costing more to haul cement from Jamul to San Diego than it costs to bring English Portland cement to California by vessel. The cement made by this company has been quite extensively used throughout Southern California.

ASBESTOS.

The John D. Hoff Asbestos Company, of San Diego, is operating an asbestos mine in the San Jacinto Mountains, from the product of which a variety of fire-proof material is made, including roof paints, roofing, boiler and steam-pipe covering, fire-clay goods, etc. This is the only asbestos concern in the southern part of the State, and the business seems to be on the increase. The works are located near Pacific Beach, 7 miles from San Diego. Asbestos is also found near Palm Springs, in the San Jacinto Mountains, and several miles east of Indio.

PINACATE DISTRICT.

Near the line of San Bernardino and San Diego Counties, about 5 to 8 miles west from the town of Perris, are the mines of the Pinacate District, all being veins of quartz-bearing gold. In past years this district has produced a large amount of bullion, the quartz being worked in arrastras, the beds of over a hundred of which still may be seen scattered about.

There are numerous springs of small size in the district, but timber is very scarce. The formation is syenite and granite principally; occasionally schistose and gneissoid rocks and quartzites being observed. The entire region is metamorphic, excepting a few dikes of granite (pegmatite) and quartz porphyry. Diorite is found near the Good Hope Mine. The region is one easily accessible, and but 4 to 8 miles from a railroad.

STEELE’S MINE.

To the northwest of the Good Hope Mine is the Victor Mine, formerly “La Plomo.” This mine is now better known as the Steele Mine. The vein is a foot or more in width, consisting of a highly crystalline quartz, in which is disseminated a small amount of iron and lead sulphuret and lead carbonate. The rock is quite rich in gold, some of it showing gold without the aid of a lens.

A tunnel 900 feet in length had been run to develop the vein, on which an inclined shaft had been sunk to a depth of 200 feet. Besides this work there were numerous other superficial workings, in which quartz of good grade was exposed. The vein occurs in a region of metamorphic rocks, the foot wall containing much quartz and biotite mica. The hanging wall is dark gray color, and quite fine-grained in texture. Hornblende crystals are plentiful throughout the rock. Other rocks in the vicinity are mica schist, chloritic rocks, quartzite, and other more massive crystalline rocks. Granitic dikes (pegmatite) cut the formation on all sides, none of them being very large. These dikes are characterized by their exceptionally coarse crystallization. Good-sized tourmalines, of jet black color, are numerous in the granite.

THE ROSALIA.

About a mile northwest from the Victor is the Old Rosalia, now the Santa Rosa, which is opened along the surface for over 1,000 feet by cuts and shafts. The upper portion of the vein was worked out years ago, but new capital has been interested and a new shaft was being sunk at the north end of the property.

The inclosing rock on either side of the vein is very soft and much decomposed, requiring more timber than had ever been used by the former operators. The mine has produced a large amount of gold, which was extracted by working the quartz in arrastras, and in later years in a mill, which still stands on the mine. At the north end it was understood that the shoot of pay rock was still intact, and it is to recover this that the new work was being inaugurated. The balance of the shoot to the south has all been worked out down to the water-line.

THE SANTA FE.

Not over half a mile from the Rosalia is the old Santa Fe Mine, which in days gone by was a producer of gold, but its workings had long been abandoned.

THE SHAY MINE

Is also in the Pinacate District, 6 miles west of Perris. Several holes have been sunk on the vein, but the entire lower portion of the mine was flooded and could not be examined. The quartz is a bluish, ribbon-like rock, and carries considerable gold. The owner from lack of means is unable to work the mine.

There are numerous other mines or veins in the district, many of which have been worked in former years by Mexicans, who coyoted about, working the narrow seams and crushing the quartz in arrastras. These veins are now abandoned, and no one seems to have sufficient faith in their value to undertake anything like systematic development. The veins mostly lie quite flat in granite or syenitic rocks. They are usually from 4 to 16 inches in thickness and extend some distance. Roads are constructed to nearly all of them. It seems like a region promising good returns on small investments. One ten-stamp custom mill could crush the rock for all the veins of this district. I was informed that much of the rock returned from $60 to over $100 per ton.

THE MENIFEE MINE

Is located south of Perris about 8 miles. The vein contains gold-bearing quartz. The foot wall is a chloritic schist, back of which lies a syenitic rock. The hanging wall is syenitic granite, the hornblende having changed partly to chlorite. The vein is from 1 foot to 30 inches in width, and strikes northeast and southwest, dipping west 80° to a depth of 40 feet, where it flattens out to 65°. The quartz mills about $15 per ton, and contains but a small percentage of sulphurets. There are four shafts on the vein, varying from 35 to 60 feet in depth, the main shaft having a double compartment, being 5 by 11 feet. They have a five-stamp mill.

THE WALKER CLAIM.

Within a mile of the Menifee, in a northeasterly direction, a new discovery was made in the spring of 1892 of a quartz vein which occurs on a low mound at the base of low, rolling hills. The vein was small, 4 inches to a foot, quite heavily mineralized, but much broken. Two distinct faults occurred in a length of 90 feet, where the vein had been exposed. Two shafts were down 30 feet each, and water was coming in. The finding of specimen rock had created quite an excitement in the vicinity, and visitors were numerous. The rock, I judged, would pan out about $40, but too small an amount of work had been accomplished to make any estimate of the value of the vein possible.

CARGO MUCHACHO MINE.

In the Cargo Muchacho District, 30 miles in a northerly direction from Yuma, the Cargo Muchacho Mine has again been in operation within the past two years. The owners moved the mill from the Paymaster Mine to a site near the former property, laid a double pipe-line 14 miles from the Colorado River, and have supplied the camp with water in this manner. The latest reports from the district are to the effect that the mill and mine are being operated steadily, with satisfactory results.

THE PASADENA MINE.

About one mile north from the Cargo Muchacho is a vein on which several locations have been made. Of these the Pasadena and Peterson claims are most prominent. The vein covered by the locations has been quite extensively opened, and possesses many of the features of the Cargo Muchacho.

The quartz was sent, at no small expense, to a mill at El Rio, on the Colorado River. The expense of mining was seldom less than $2 a ton; transportation to the S. P. R. R. at Ogilby Station, 6 miles, $250; transportation by rail to El Rio, 14 miles, 50 cents a ton, making at least $5 a ton. The mill was leased at $10 per day, to which the expense of milling was added, making fully $4 a ton more, or about $9 in all. It was claimed that the rock averaged $16. Doubtless some of it did, but it is probable the expense really exceeded the figures given.

With water pumped into the district it is quite possible that this mine, and the Peterson claim adjoining, may be operated at a profit, which under former conditions was impossible. There are many other gold-bearing veins in the region, but none of them are extensively developed.

EAGLE MOUNTAIN.

Unusual activity has characterized operations about that portion of the Colorado Desert, about 90 miles east of the San Bernardino Mountain, near the line between San Diego and San Bernardino Counties. The Eagle Mountain District is one of these localities. The discovery of rich placers in the dry gulches of that section resulted in a more thorough investigation of its mineral resources and in the finding of some very rich gold-bearing quartz. Considerable work has been done on these claims and the prospects are considered very flattering.

A cemented basin has been constructed to catch the rain water that falls during the winter season, with which it is intended to work the placer mines. The discoverers of these mines, it is said, took enough gold from the gulches, in making the basin referred to, with a dry washer, to pay for making and cementing the basin.

COTTONWOOD SPRINGS.

Twenty-six miles in a northeast direction from Walters Station, on the line of the S. P. R. R., at an altitude of 3,004 feet, is Cottonwood Springs. A range of mountains, in which occur granitic and metamorphic rocks and eruptive dikes, strikes east and west across the desert, and in these occur several springs. There is but one mine in the immediate vicinity of the springs, and this is known as

THE COYOTE MINE,

Where a reading of the aneroid indicated 3,300 feet. The formation in which the Coyote vein has formed is micaceous and hornblende schist and gneissoid rock; hornblende granite and dikes of diorite also occur in the vicinity of the vein. The Coyote Mine is a quartz vein from 2 to 4 feet in width. The rock is iron stained and occasionally shows free gold. The vein is developed by two shafts, one about 20 and the other nearly 80 feet in depth, and strikes 5° north of east, having a dip of 46° to the south. The vein appeared to cut the formation at a small angle. A fault, which has occurred within the vein, had evidently puzzled the owners, as at the bottom of the 20-foot shaft they had developed 8 feet of what looked like solid quartz. The vein is really but 4 feet in width at that point, but the fault cutting downward at an angle of 45° and crossing the strike of the vein at an angle of 27° had allowed the hanging wall side of the fault to slip downward, thus doubling the width of quartz, which was much shattered. The miners had quit work, leaving what they considered well enough alone. In the deeper shaft the fault had carried the hanging wall down and to the east a few feet, and the vein was lost altogether. A short drift had been run into the hanging wall, but not finding the vein, work had been suspended. The vein lies on the foot wall side and not more than 4 or 5 feet from the line of the slip.

FAULT OF COYOTE MINE
COTTONWOOD SPRINGS

SALTON LAKE.

By E. B. Preston, E.M., Assistant in the Field.

The Coahuila Valley, in which Salton Lake is situated, is 90 miles long and from 10 to 30 wide. It separates the San Bernardino range of mountains from the San Jacinto, and forms a part of the great Colorado Desert in San Diego County. In its deepest portions it is 275 feet below the level of the sea; the area of the depressed region is over 1,600 square miles. In its northern portion the valley consists of sandhills and dunes, the former caused by the accumulation of the sand around the scrub and bushes growing in the desert. The southern portion is bare clay. On the borders of the desert palm trees of the fan palm variety occur in a few scattered clusters. The Southern Pacific Railroad passes through the valley on its way to Yuma.

In that part of the depression adjacent to the railroad station of Salton is a salt marsh, where the New Liverpool Salt Company’s works are located, and where a fine quality of table salt is produced, containing, according to an analysis made by Thomas Price, of San Francisco:

Chloride of sodium 94.68 per cent.
Calcium sulphate .77 per cent.
Magnesium sulphate 3.12 per cent.
Sodium sulphate .68 per cent.
Water .75 per cent.
100.00 per cent.

The brine from which the salt is obtained shows a density of 27° BaumÉ.

The company’s works are situated about 3,000 feet west of the railroad track, and consist of the salt mill and a large storehouse, connected by track with the main line. This branch line extends into the marsh a distance of over 10,000 feet. Beyond the end of the track a borehole was sunk by the company, with the expectation of obtaining water, to a depth of 300 feet, when the work was interrupted.

The strata passed through during the sinking throw some light on the past condition of the desert depression, as well as furnishing some points that may have a bearing on the flooding of this section.

The top covering consists of 6 inches of black mud, resting on a crust of chlorides of sodium and magnesium, 7 inches in thickness. The drill on passing through this crust dropped through 22 feet of a black ooze, containing over 50 per cent of water. Tests of the ooze made at the State Mining Bureau laboratory showed it to consist largely of chlorides and carbonates of sodium and magnesium, the soda salts predominating, besides fine sand, iron oxide, and clay, and a small amount of organic matter. The ooze was resting on a hard clay bottom, through which the drill passed for the entire remaining distance, only varied by two or three streaks of cement. From the shore line of the marsh toward the adjacent mountain ranges, the soil consists of a fine sand, containing clay and a notable quantity of mica, and is strewn with well-preserved shells of Planorbis ammon, Gould, Physa humerosa, Gould, and Amnicola protea, Gould.

In a few spots near the northwest end of the marsh the accumulated cases of a species of Caddice worm are found. Northeast of the marsh the surface slopes gradually upward to where the remains of an ancient sea beach are to be seen, stretching to the south and east to where the Colorado River cuts through on its way to the Gulf of California.

Behind the beach extends a mesa to the foot of the San Bernardino range. Across this mesa are evidences of heavy floods coming down the caÑons of the back range, carrying large quantities of debris with them, mostly bowlders of mica schists and granitoid rocks, with some quartz intermixed. On the west side of the marsh the surface has but little elevation until the granitic bluffs of the San Jacinto range are reached. These bluffs are coated for a distance of about 25 feet above the plain with a sponge-shaped incrustation from 2 to 3 inches thick, consisting largely of carbonate of lime, chloride of sodium, sand, clay, and oxide of iron; under the glass some of the pores are seen to contain minute shells of the same varieties as found on the sand of the plain. Where arroyos have been cut through the sands of the plains to the depth of several feet, the exposed sections show a stratified arrangement of the sand, having between the layers a thin division of the same varieties of shells as found on the surface, the whole resting on a firm clay bottom. From the position and regularity, as well as the quantity of these shells, on top of the different strata of sand, while but few are seen scattered through the sand layers, a periodicity of the conditions favorable to their existence and growth, as well as a comparatively sudden cessation of the same, must be inferred. These conditions mean an occasional flooding of the depression for a period of time, during which a shallow body of water was maintained, which evaporated as soon as the water supply was shut off. In what manner this can occur will be shown later on. The plain supports a scant growth of desert shrubs, with some mesquite bushes in the vicinity of the few springs that are found scattered over the desert, most of which are saline. The presence of the extensive line of sea beach proves that at some time the gulf has extended much farther inland than at present, covering the whole of this depression. The Colorado River, in its course south to the ocean, built up a flood plain on a higher level that finally shut off the western part from a direct communication with the sea, and evaporation, with a gradual uplifting of this whole section, finally laid it bare, although leaving a great part of it still below the present sea-level. Under these conditions, whenever more water comes down the river than its banks can contain, the silt-formed shores give way to the increased pressure and permit the excess of water to flow to, and gather in, what is termed the river swamp at the back of the flood plain, from whence it either re-enters the river lower down in its course, or finds its way into the depression.

The Salton Marsh at present acts as the catchment basin for the waters draining from the east side of the San Jacinto range, Carizoo Creek, and a part of the San Bernardino Mountain range, and in times of extreme high waters as a reservoir for the excess in the Colorado River. In the month of June, 1891, a steady flow of water entered the depression from the southeast and continued to the northwest uninterruptedly until an area 30 miles long and averaging 10 miles in width was covered to a depth of 6 feet, measured at the end of the Salton Salt Works branch track. When first examined the water showed a density of 7° BaumÉ, which gradually increased to 25° BaumÉ. The mother liquor used in making salt at the New Liverpool works usually shows a density of 27° BaumÉ. This salt water gave rise to the idea that the waters from the gulf had made an inroad through some underground channel, and to prove the source and possible permanency of these waters several investigating parties were sent out. No such previous incursion had been witnessed by the settlers, but inquiry proved that a similar lake existed here in 1849. Finally one of the parties showed that the Colorado River was the source, and then the question was brought to the attention of the State Mining Bureau to investigate as to the probability of the permanency of the lake and its probable effect on the climate of the surrounding country.

The Colorado in its great length accumulates a large amount of sediment, from 0.1 to 0.4 per cent per gallon, and after this has been deposited the water on evaporation is found to contain 0.14 grammes solid residue, consisting largely of sulphate of soda and chloride of sodium. With the sediment the river is all the time building up its flood plain, and it may not be out of place to recall the general laws that govern the actions of streams while depositing the solid matter they carry in suspension.

Currents bearing sediments deposit a large percentage as soon as their velocity is checked in the least, but pick up deposited sediments again as soon as the current is increased. Thus a variable current is depositing at one point while eroding deposits at other points.

The velocity of a river current varies with the seasons on account of the different volumes of water carried, but it also varies at different points of the river, during the different hours of the day, through the constant action of the laws of erosion and deposition. The banks not furnishing a constant, even resistance, erode in the looser parts, causing each time a deflection of the current, as well as a change in the velocity. This action soon changes a straight stream with an even current, to a serpentine course with currents of different velocities, as the outside of a curve has always greater speed than the inside; consequently the outer edge is eroding while the inner is depositing sediment. The Colorado River, in the lower part of its course from Yuma down, overflows its flood plain, and deposits thereon a certain amount of sediment during every high water. This flood plain extends back for several miles on the west bank, showing a succession of benches or levees running parallel with the stream on a higher level than the back country. The water, when high enough to reach over these benches, gathers in the back part, where it evaporates, leaving a mud that greatly enriches the soil. These levees are the result of the law quoted above, as the water in the regular channel flows swifter than on the flood plain; consequently on the border of the two a large amount of sediment is thrown down. As these border lands are only covered during the highest floods, they maintain a growth of willows and poplars that gives the banks a greater stability, and preserves them to a certain extent from the erosive force of the current.

A source of changes in the direction of the main current is the stranding of logs and tree tops brought down from the upper courses of the river, as the sediment accumulates behind them and forms islands in midstream. Several of these are to be seen in the river channel in passing down the stream.

From soundings made across a section of the river at the railroad bridge at Yuma, the depth was found to vary from 2½ feet to 21 feet. At the meter placed in the main channel the indicator showed a depth of 17 feet.

At ordinary high water, caused by the annual rising of the Gila River, or of the Colorado in its upper reaches, which events usually occur at different seasons of the year, the meter has not been known to show a depth of over 28 feet, but in consequence of a co-equal rise in both streams during the past season, the meter registered over 33 feet. This excess filled the river swamp on the right bank, where the erosive force of the current was most effective.

The course of the river below Yuma for several miles is to the west, until the neighborhood of El Rio station is reached, where sandstone bluffs on the right bank deflect the current back to its general south course. A little back from the river below this point is a small, isolated range of hills, known as Pilot Knob, formed of granite, fissured with seams of dioritic rock. The granite shows lamination, and the surface of the rocks is polished by the constant attrition of the drifting sands. The beach near Pilot Knob is cemented into a calcareous conglomerate, underlaid by sand in a loose state. After resuming its southern course the river for several miles follows a straight reach, until below Hanlon’s Ferry. The tendency of the current to bear more to the right bank shows itself now in the formation of sloughs and inlets that absorb a large proportion of the water and form several islands, shallowing that part of the river that passes down the proper channel.

SECTION OF COLORADO RIVER AT YUMA

DETAIL OF BREAK
IN
COLORADO RIVER

The accompanying sketch shows the different channels in detail. Formerly the water from these outside channels returned through the bend marked “sand” to the main stream, but at the present time it passes through a crevasse in the bend, marked Tapscott and Carter Rivers, furnishing the largest portion of the water that ultimately found its way into the depression of Salton Lake. During the extreme high water the western bank from El Rio down, which is formed entirely of silt, was broken through in numerous places, and the mostly shallow channels either entered the river again below, or accumulated their waters on the back part of the flood plain, and by following the natural hollows and gullies gradually wound their way in the direction of the old Yuma road. The great force of the current soon cut down below the level of the river bed and relieved in part the congested condition. The grade being gradually to the west, the water cut through the sediment in that direction, partly to the Yuma road, partly farther south parallel to the Rio El Medio, which, judging from analogy, owes its origin to some former similar condition of the river.

Tapscott River may have been formed prior to Carter River, as it has a better defined channel; the latter has no regular channel, but seems to have been caused by the excess of water that could not enter the former, following depressions and sloughs which have no direct connection with one another. At the time these observations were made, the estimated volume of water in the river at the Yuma bridge was about 3,700 cubic feet per second, and at the crevasse forming Tapscott and Carter Rivers, two fifths of the entire volume of water in the river was passing through, but none of it was reaching Salton Lake. Of this two fifths not more than 20 cubic feet per second was running through Carter River.

Beyond Alamo Mocho, which is on the old Yuma road, at the time of the flood, the water flowed into a number of lagoons, and thence into New River, following the old channel that was cut at the time of the 1849 overflow, and thus reaching and forming Salton Lake. All of the water leaving the main river at present finds its way down through the Hardy Colorado back to the Colorado proper, or evaporates.

In the beginning of this article mention was made of a borehole that was sunk by the new Liverpool Salt Company in the salt marsh, and which revealed under a thin crust of mud and salt a depression filled with ooze, composed largely of magnesium and sodium salts. This ooze is probably the final resultant of the evaporations of the former sea water, and which, from the well-known avidity of the magnesian salts for moisture, is kept in this condition of ooze through the natural drainage and seepage waters. This depression may extend beyond the borders of the present marsh toward the gulf, covered over by the sand, and may have some relation with the small so-called mud volcanoes southeast of the lake near the station of Volcano, as well as with some openings in the ground mentioned by one of the gentlemen who investigated these regions between the Colorado River and the lake, and of which he stated that any amount of water running into them did not seem to fill them. Should such a connection exist, the water pouring in from the river would have dissolved the thin salt crust where exposed, and opened a channel, permitting a rapid filling in of the water which formed the lake, for otherwise a body of water running over this light sand and under such a dry, hot temperature would hardly have filled up the depression as rapidly as was the case. Besides, this would explain the reason for the fresh waters of the Colorado River attaining so rapidly a density of over 20° BaumÉ. Should this supposition prove correct, and it could easily be ascertained by a series of shallow boreholes, it might be expected that every large overflow in the Colorado River in this direction would result in a repetition of Salton Lake.

                                                                                                                                                                                                                                                                                                           

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