Popular Science Monthly/Volume 82/March 1913/The Sweden Valley Ice Mine and its Explanation
|THE SWEDEN VALLEY ICE MINE AND ITS EXPLANATION|
LEHIGH UNIVERSITY, SOUTH BETHLEHEM, PA.
THE Sweden Valley Ice Mine, one of the unexplained mysteries of nature, is located about four miles east of Coudersport, the county seat of Potter County, Pa. A similar phenomenon is situated on Dingman Run, about three miles west of Coudersport. These are natural ice-manufacturing plants, running under full head during the warm season of the year, but shutting down entirely during the cold months of winter, when there is plenty of ice and snow to be had elsewhere and when it would seem to be the most natural time for the formation of ice at these places.
To learn something of the history of the Sweden Valley Ice Mine we must go back to the time when the Indians were the chief inhabitants of this particular section of the country.
A certain tribe knew the location of deposits of silver and lead, which they carefully guarded against discovery both by other bands of Indians and by the few white settlers in that vicinity. As the whites became more numerous the Indians were driven farther west, taking their mineral secrets with them, as well as the scalp of one white hunter who accidentally discovered one of their lead mines. For years accounts of these mines were handed down from one generation to another, until, having become partially civilized, the Indians returned to recover, if possible, some of their lost wealth. They came in bands of five or six and searched the country thoroughly in the vicinity of Coudersport and Sweden Valley, but without success. The country had been so changed by the advance of civilization that they were unable to follow the directions given them by their ancestors and were finally obliged to abandon the undertaking.
These strange, unexplained actions on the part of the Indians naturally aroused considerable curiosity among the residents. They surmised that the Indians were searching for minerals, and the ground was again thoroughly gone over, but with no better success.
A year or so later, in 1894 or 1895, a Cataraugus Indian came to Coudersport, got a lunch and walked off into the woods. After some time he returned with some fine specimens of silver ore which he exhibited to the amazed loungers who gathered around him. He then disappeared without telling any one where he was from, where he secured the ore or where he was going.
The result of this visit was only natural. Silver mining was the topic of conversation whenever two or more persons got together. Another search was organized which resulted in the discovery of the Sweden Valley Ice Mine.
Mr. John Dodd and Mr. William O'Neil were prospecting near Sweden Valley when, underneath four or five inches of moss, they found a thin layer of solid ice. After leveling off a space about fifteen or twenty feet square they dug a shaft about six feet square by twelve feet deep. At a depth of nine feet they found petrified wood, impressions of leaves, ferns and other vegetation, also bones which were pronounced to be human. At a lower depth a peculiar kind of rock was found which they thought might contain gold or silver. Some of this
was assayed and found to be of no value. At a depth of twelve feet an aperture was found from which came a cold draught. This was thought peculiar, but nothing was done to investigate farther and the work was abandoned.
The following spring Mr. Dodd found a considerable amount of ice in the mine, but thought that it had gathered there during the winter and had not yet melted. However, as the warm weather advanced, the quantity of ice instead of melting as was expected, began to increase, and by the middle of July the sides of the shaft were covered with a coating of ice a foot or more thick and large icicles were forming from the opening at the top.
As winter again came on, the ice began to disappear until the cave
was nearly free from the summer's product. This phenomenon has regularly been repeated each year since its discovery.
Mr. Dodd, who owns the land; had a small building erected around the mine, leaving the roof, directly over the shaft, open so as to allow the rays of the sun to beat in upon the ice formation. The beautiful woods surrounding this spot make an ideal place for picnics and it has become a favorite place for visitors to spend an afternoon, and incidentally cool off.
Two years ago (1910) the bottom of the shaft settled eighteen inches, leading to an experiment by Mr. Dodd. He says that two sticks of dynamite were placed about eight feet back into a crevice at the bottom of the shaft and fired without turning a stone or dislodging any earth in the shaft. A possible conclusion is that there is a cave underneath the mine large enough to absorb the shock of the explosion. Nothing more has been done in the way of investigation.
The Dingman Run Ice Mine is a more recent discovery, being found on June 15, 1905, on Dingman Run on the farm of Mr. Pelchy. Mr. Pelchy, with the help of another man, was clearing up some brush-land for farming when, in order to get a better foothold on the steep hillside, he tore away a little of the moss, which was several inches deep at that place, and found pieces of ice.
Having heard of the ice mine at Sweden Valley he began to dig in the hope of discovering a similar phenomenon on his own farm. He made an opening in the hillside ten feet deep by twenty across, finding crevices in the rock from which he took chunks of ice weighing twenty and twenty-five pounds. Nothing more was done to bring this mine to the notice of the public and consequently it is known to but very few people even in Coudersport.
Although the Sweden Valley Ice Mine was discovered in 1898, it is practically unknown to-day. It is astonishing how many people within a few miles have never visited it nor heard of it. Recent inquiry (March, 1912) at the United States Geological Survey, Washington, brought forth the following response:
The reason the U. S. Geological Survey has no record of these phenomena is that their survey in Potter County has never been completed and no atlas of the county has ever been published.
Further inquiry brought the following reply:
We find that phenomena similar to that described by you are not unknown and have been discussed in numerous papers. One of the best of these is the article on the Decorah Ice Cave and its explanation by Mr. Alois F. Kovarik, Scientific American Supplement, November 26, 1898, pp. 19158 and 19159. Dr. Samuel Calvin in his geology of Winneshiek County, Iowa (Iowa Geological
Survey, Vol. 16, 1905, pp. 142 to 146), describes this phenomenon and quotes at length from Mr. Kovarik 's article, with approval. See also "Glaciers and Freezing Caverns," by Edwin Swift Balch, Philadelphia, 1900, pp. 88, 89, 177, 136 to 161; also "Ice Caves and Frozen Wells as Meteorological Phenomena," by H. H. Kimball, Monthly Weather Review, Vol. 29, pp. 366 and 509, 1901.
The writer looked through these references hastily and from Balch's "Glacieres or Freezing Caverns" the following is taken:
The belief of the peasants is founded on the fact that they scarcely ever go to any cave except when some tourist takes them with him, and, therefore, they rarely see one in winter, and their faith is not based on observation. It is, however, founded on an appearance of truth: and that is on the fact that the temperature of glacière caves, like that of other caves or that of cellars, is colder in summer than the outside air, and warmer in winter than the outside
Professor Thury tells a story to the point. He visited the Grand Cave de Montarquis in midwinter. All the peasants told him there would be no use going, as there would be no ice in the cave. He tried to find even one peasant who had been to the cave in winter, but could not. He then visited it himself and found it full of hard ice.
While the writer does not claim, as these peasants, that the heat of summer is the direct and only cause of the formation of ice, he does hold that it is an indirect cause and that the ice to be seen in the Sweden Valley Ice Mine is formed after the temperature outside the mine is far above the freezing point, and it is when the temperature outside is the highest that the ice is formed the most rapidly. The cause of this will be explained shortly.
The general skepticism regarding the existence of this phenomenon has been illustrated many times of late and has furnished the people of Coudersport with an endless source of amusement.
In the early part of the summer of 1911 a certain man of Detroit, Michigan, came to visit relatives in Coudersport. He was, of course, taken to see the ice mine, which was in its prime at that season of the year. Upon his return to Detroit he wrote a short article for one of the Detroit papers in which he told of this wonder that he had seen near Coudersport and offered to bet any one and every one $100 or more that his fictitious-sounding story was true. A millionaire ice manufacturer took the bet and eight other business men of Detroit followed suit. Two newspaper men were selected as stake-holders to decide the
bets. They visited the mine and, of course, verified the newspaper story, much to the disgust of the nine losers.
It is claimed by a great many persons who hear of this phenomenon, never by those who actually see it, in the summer time, that the ice is not formed during the summer, but is only an accumulation from the preceding winter. It was to prove the falsity of this claim that the writer visited the mine many times during the winter and spring of 1912. The existing conditions were found to be as follows:
The pit or shaft is about eight feet in diameter by twelve feet deep and, as shown in the sketches, is located at the base of a steep hill. In the winter time the pit is comparatively dry and free from ice. The temperature inside is the same as that prevailing outside. In the spring of the year, as the snow on the hillside begins to melt and the frost comes out of the ground, water naturally begins to trickle down the sides of the shaft, where, strange as it may seem, it is frozen in the form of small icicles. This freezing process continues, until by July the sides of the pit are completely covered with a coating of ice a foot or more in thickness. In the early fall the process stops and the formation of ice gradually melts. The sides of the shaft are of loose shale, in which there are numerous crevices extending back and up into the hill, the rock strata being rather sharply inclined. A draught of cold air, which at some places is strong enough to extinguish the flame of a small taper, issues from these fissures in the summer time. This draught is variable, being stronger on hot than on cool days. A heavy mist may also be seen rising out of the pit and floating off down the hill close to the ground. The temperature of the pit during the past summer varied between 25 and 32 degrees Fahrenheit.
The explanation of this phenomenon appears to lie in the cold currents of air issuing from the crevices of the rocks along the sides of the shaft. The air must gain access to these fissures at some other point, which must be at a higher altitude than that of the pit, as will be seen from the following discussion.
This being true, it is evident that in the winter time the column of air directly over the pit is cooler and consequently heavier than that in the rock passages. Therefore, it forces its way down into the pit and up through the rock strata, chilling the rocks to a great depth and storing up a vast quantity of "cold." We see, then, that the amount of "cold" which is stored up, or the depth to which the rocks are chilled at the beginning of warm weather in the spring, depends upon the length and severity of the winter.
As the warm weather comes on the column of air over the pit becomes heated and is displaced by the cold, heavy air flowing down out of the passages. This cold current of air freezes any surface water which flows over the edges of the pit and maintains a freezing temperature as long as the supply of "cold" in the hill lasts, after which the circulation of air ceases and the ice formation melts.
The place at which air gains access to these passages need not be a single opening, but consists, in all probability, of numerous small apertures, covered possibly by a thin coating of moss, loose shale or other porous substance.
In the summer time the warm outside air entering these apertures comes in contact with the rocks which have been chilled by the reverse currents of the preceding winter and in doing so gives up its heat to them, becoming specifically heavier. It then forces its way on down, displacing the warmer and lighter column of air above the pit.
It is evident that the rapidity with which this circulation takes place depends upon the difference in temperature of the two air columns. That is, the cold outward current is much more noticeable on hot days than on cool days in summer, and in winter the strongest inward current is noticed on the coldest days.
This fact accounts for the common belief that the freezing takes place more rapidly and that the mine is colder on hot than on cool days.
The temperature of the mine, or, in other words, of the air as it issues from the crevices, remains practically constant throughout the summer, which is proved by thermometer readings. However, the difference between this constant temperature and the temperature prevailing outside the mine is obviously greatest on the hottest days and therefore, as one enters the mine, the contrast is more noticeable. This causes one to believe that the mine is colder when it really is not. It is true, however, that the ice is formed most rapidly during the hottest weather. This is not because the temperature of the mine is lower, as is generally supposed, but is due to the fact that the circulation of air is more rapid; that is, a greater quantity of cold air issues from the numerous apertures and consequently a greater amount of "cold" is available for the formation of ice.
As soon as the supply of "cold" in the rocks is exhausted the internal and external air columns become gradually equal in temperature and weight, the circulation ceases and the ice begins to melt. This generally occurs about September of each year.
If this is the true explanation of this phenomenon, we may say, with truth, that in this particular instance it is the heat of summer which causes the ice to form, but, at the same time, we can not disregard the fact that it is the severity of the preceding winter and the natural arrangement of the rock strata which make it possible for the heat of summer to produce this peculiar phenomenon.