CHAPTER LXVII.

BELOW THE WATER-DEPOSITS.

In countries where no mining is done it is the prevalent opinion that at a certain depth the earth is full of water, and that the deeper we go the more water will abound. This is a mistaken notion. After delving beyond certain bounds, water ceases to be generally disseminated in the earth. This is after we have gone below the “scalp” or surface-water of the country. Until we have passed through this scalp, water is found almost everywhere. This being the case, it is quite natural that persons residing in countries where wells sunk in search of a supply of water are the deepest works of the kind undertaken, should imagine overwhelming floods of water to exist everywhere far down in the bowels of the earth.

In Nevada—and the rule probably holds good in every country—after passing the more open and softer matter—drift and rock—there is reached the solid rocky mass forming what might be termed the “skull” of the earth—the hard shell lying between the comparatively spongy exterior strata, and the molten interior mass. This intermediate shell of hard rock is where the miners along the Comstock are now delving in all the deeper mines. Here we find that solid rock takes the place of water in most situations—solid rock is the rule. When the rock is not solid and perfectly homogeneous, there water finds its way and forms subterranean reservoirs of all sizes and shapes, which, in mining parlance, are called “pockets.”

These pockets may be of almost any shape, but are generally in the form of a crevice. As a rule, the crevices are not open spaces like caverns, but are filled with some permeable material into which the water may find its way and settle, as in the ground composing the “scalp” above.

The water at the depth of from 1,000 to 2,000 feet lies in detached bodies. In the country-rock (the rock lying on each side of a vein and forming the general rock of the country) there are fewer of these pockets of water than within the bounds of a vein, as the solidity and homogenous character of the outside rock leaves no space in which water may be contained. The Comstock lode occupying an immense fissure, extending into the intermediate crust of the earth to an indeterminate depth, there are naturally many openings in it, through which water may descend; besides, the material of which the vein is composed is in general much softer, and therefore more pervious than the great mass of rock outside of the vein. The pockets of water are confined within walls of clay or hard, impervious rock. Thus drifts may be run on all sides of, and even under, these subterranean reservoirs, and no water is seen until the confining walls are cut. When a body of clay is encountered and there is reason to suspect that a body of water is being approached, a long drill is used with which to feel the way in advance of the drift, and let the water out, if any there be, in a controllable stream. Were the miners to push ahead with a drift of full size, the pressure of water would presently burst in the whole face of their opening, tear down the timbers, cause extensive caving of the ground, and perhaps flood everything and drown the men before they could escape.

When once the works of a mine have been carried down into the solid shell of the earth, the work of draining any body of water that may be encountered is a mere question of time. If the underground cistern is small it is soon pumped out; if large it takes a proportionally longer time, the same pump being used in each case; but, sooner or later, it must be exhausted. If water were not thus found in detached bodies (instead of being universally diffused) in that zone of the earth under consideration, there could be mining under seas, lakes, and rivers, as is now successfully practiced in many countries.

In illustration of the manner in which miners often drift under and around bodies of water, I may give an incident of the early days of Washoe, when drifts and tunnels had not yet drained off the surface-water, and wells were yet a possibility in Virginia City.

[Illustration: THE MISSING WELL BOTTOM.]

A lady resident of the town one day went to a well in her door-yard to draw some water. Being in haste, she let the bucket go down from the windlass “by the run,” and the instant it struck the water out dropped the whole bottom of the well. Every drop of water instantly disappeared and nought was seen where it had been, but a black, yawning chasm in which hung and dangled the bucket. Amazed almost beyond the power of speech, the lady for a time stood and gazed into the bottomless well, then rushed to the house. She had considered the matter and comprehended it.

“What did I tell you?” cried she, addressing her rather easy-going husband. “I knew that the men who dug that well were taking no pains with their work!”

“What is the matter now?” said the husband.

“Matter?—matter enough! The bottom has dropped out of the well!”

“Bottom dropped out of the well!” exclaimed the husband, beginning to become interested.

“Yes: the bottom has dropped out of the well, and I am not at all surprised—I am not one bit astonished! I knew when I saw the men putting the bottom in that well that it would never be of any account!”

The cause of the accident was simple enough. The well had been dug in the line of a tunnel advancing from a distant point below. The miners, all unconscious of the presence of the well, had drifted under it, and at no great distance below its bottom. Being without adequate support the bottom must soon have fallen out, of its own accord, but the sudden jar of the bucket on the surface of the water undoubtedly precipitated the event. A peculiar kind of clay is found in many places on the Comstock lode which is not a little curious on account of its creeping propensities. A stratum of this clay will be seen to crawl out into tunnels and other openings in a manner much resembling the action of the toy known as Pharaoh’s serpents. You are unable to see where it is coming from or what moves it, yet it is constantly crawling out into all the openings that reach it.

In places where drifts have been run into this clay it is necessary to keep one or two men constantly at work at cutting it away in order to keep the drifts open and passable. This is not owing to the slaking and swelling of the exposed surface, as in that case after a few removals of the surplus material a hole would be left, and there would be no more trouble. The whole body of the clay appears to be creeping. It has the almost imperceptible motion of the glacier, irresistibly advancing, crushing everything in the shape of timbers that may be placed before it. All that can then be done is to set men to work at cutting it off as fast as it comes out. The cause of this creeping is probably to be found in the pressure, of the superincumbent or surrounding strata of rock. Its motion is not unlike that seen in the straightening out of a piece of pith that has been compressed. There is a limit to this creeping power of the clay, but it is not reached till many feet have crept out into the drift, tunnel, shaft, or chamber, and have been cut off and removed. Its actions is so mysterious that some of the miners are ready to explain it by saying that the clay comes out and fills up the drifts because “Nature abhors a vacuum.”

If left to its course the clay would very soon close up the drift, as completely as if none had ever been made. Thousands of feet of drifts and tunnels in the mines are closed in this way.

In the Caledonia mine, American Flat, much trouble was experienced with this creeping clay. On one occasion a streak of it two or three feet in width continued to rise from the floor of a tunnel until over thirty feet had thus come up and been cut off. It is bad anywhere, but is most mischievous in the main shaft. For this reason mining men always seek a spot in which to put down such shafts, where they are likely to pass through solid “country-rock” to a great depth below surface. The sad experience of early days taught them this lesson. The clay is generally found within the wall of the vein. It abounds in the mines south of Gold Hill, about American Flat. The ordinary clay found next to the foot, and hanging walls in all mines is liable to swell—on account of the lime it contains—when exposed to atmospheric action, but after the pressure on the timbers has been eased by cutting away behind them a few times, there is no more trouble.

The power of this swelling, slacking clay is immense. It crushes in, and splinters all the timbers that can be placed before it: it somewhat resembles the power exerted in the expansion and contraction of large masses of iron, as seen in iron bridges and similar structures. The following curious Comstock “find” may be of interest to some readers.

In working out the first or upper bonanza of the Ophir mine, there was brought to light a human skull of a very ancient and curious type. The skull was dug out where a drift was being run in the ore-body at a depth of about three hundred feet below the surface. It was brought out, and dumped with a car-load of ore, not being observed by the miners. United States District Judge A. W. Baldwin, since killed by a railroad accident in California, happened to be present when the car-load of ore was dumped. Seeing an object of peculiar shape roll toward his feet among the ore dumped from the car, the Judge picked it up, and found it to be a human skull of a peculiar form and thickly crusted over with sulphuret of silver. He carried it into town and presented it to Wm. Shepard, of the firm of Tinker & Shepard, who placed it in a cabinet of curiosities, where it still remains.

The skull attracted no attention outside of Virginia City until 1874, when, mention being made of it in the newspapers, the Academy of Sciences, of San Francisco, sent for it for the purpose of making a critical examination of it. While it was in San Francisco a plaster cast was made of it, and at a meeting of the Academy of Sciences, Dr. Blake exhibited the cast and spoke of it as follows: “There is in this skull a peculiarity that is seen in some of the ancient Peruvian skulls, namely, on interparietal bone. The general _contour_ of the skull is of a very low type; the anterior portion is very slightly developed and receding; the hinder portion is largely developed. It bears a similarity to the skull of the carnivorous apes, the cavity for the lower jaw-bone being very deep and not allowing of any grinding motion of the jaws. The skull when found was covered with a metallic layer. It is of a different type from any that have been found, and belonged to a carnivorous man, who could walk easier on all fours than on two feet.” Several ancient Peruvian skulls were then produced in order to show the interparietal bone.

Professor Whitney was very anxious to be allowed to send the skull to the Atlantic States and Europe, but the owners would not part with it for that purpose. The plaster cast taken was sent to Dr. J. Wyman, of Cambridge. It would seem that the conclusion arrived at in San Francisco was that the skull was that of a man belonging to a pre-historic race. He probably was adorned with a tail. At the time the great fissure was formed in which the Comstock lode was deposited, or perhaps at the time the fissure was being filled with its rich ores, this pre-historic creature was probably fooling about the edge of the chasm, looking down into it to see what discoveries he could make, when the earth crumbled beneath his weight, and he rolled down and was incorporated in the heart of the vein. His sad fate must have proved a salutary warning to all others of his tribe, as his skull is the only thing in the way of ancient human remains that has ever been found in any mine on the lode.

[Illustration]

[Illustration: THE MAN-EATER]