Art. XIII. On a singular Disruption of the Ground, apparently by Frost.

Art. XIII. On a singular Disruption of the Ground, apparently by Frost, in Letters from Edward Hitchcock, A.M. Principal of Deerfield Academy.

(With a Plate.)

To the Editor of the American Journal of Science, &c.

Sir,
I have lately examined a singular disruption in the earth, discovered a few days since in the northerly part of an extensive meadow in this town, about ten rods from Deerfield river.

The soil on the spot is alluvial, consisting of a dry, rich, vegetable mould, with a large intermixture of sand; and the field, elevated 14 feet above the bed of the river, is annually mowed. A valley encircles the ruptured spot on the east, south, and west, only five feet lower, yet so marshy and soft, as to render draining necessary to make it passable; and immediately back of this valley, on the south, rises a hill 100 feet high, at whose foot are several springs. North of the rupture, also, between it and the river, is a gradual descent of three feet: indeed, the ground slopes from it on every side except the northwest.

A fissure one inch wide and fourteen deep, forming an almost perfect ellipsis, whose diameters are 9 and 5½ rods, marks the exterior limit of the convulsion. Within this curve are several others nearly concentric to it, some forming a quarter, and some half an ellipsis, and near the longer axis are others, running in various directions. On this transverse diameter, which lies near the highest part of the swell above described, and in its longest direction, or parallel to the river, the greatest effect of the convulsion appears. The earth, to the depth it has frozen the past winter, 14 inches, is broken on a straight line above 6 rods, and the south edge of the fissure, having been forced up, overlaps the other, three feet. Where one edge does not thus overreach, the tables of earth, which at a small distance resemble masses of ice, are raised up so that their faces form an isosceles triangle, leaving a cavity beneath. About the extremities of the transverse axis, is also an overlapping of two feet, which continues nearly two rods on the curve each way from the axis, and in most places is double, overreaching internally and externally, exhibiting likewise, some irregularity where the compressing forces acted at right angles to each other. The edges of these elevated masses of earth, which are yet frozen, are quite smooth, and the angles but little fractured. I have dug into the earth about four feet underneath the longer axis of the ellipsis, and thrust down a bar in other places, but cannot perceive that the soil has been moved below where it was frozen. It is, however, not the most favourable season for ascertaining this fact.

Every appearance on the spot will justify this conclusion, that the frozen surface of the earth around, has pressed with great force from every direction to this ellipsis as a centre; for, were every fissure in the ellipsis to be filled by replacing the earth, there must remain on its longer axis and at the extremities of this, an overplus of surface two feet wide.

The month of February last has been unusually cold. Its mean temperature in Deerfield, by Fahrenheit's scales, is as follows.

7h. A. M.1½h. P. M.10h. P. M.
6°24°11°

The extremes were 25° below, and 49° above zero. On the last day but one of the month, the cold suddenly relaxed; and on the 1st and 2d of March, a heavy and warm rain succeeded. This produced an uncommon rise in Deerfield river, and on the 3d of March, it had overflowed the ground where the above described phenomenon occurred, and did not recede from it for 24 hours. Its greatest depth there, was five feet. The snow was nearly one foot deep when the flood happened, and being a nonconductor of heat, the temperature of the surface of the ground was not probably much changed from its state in February, until the water came in contact with it. It may not be amiss to give the state of the thermometer on the last of February and beginning of March.

7h. A. M.1½h. P. M.10h. P. M.Wind, weather, &c.
Feb. 27th,15°below 0.28°above 0.32°above 0.South,clear.
28th,31above45——31——do.do.
March 1st,29——46——37——N. E.rain.
2d,46——49——37——do.do.
3d,30——35——29——do.rain & clear.

On the third of March, about sunset, some lads were sailing near the spot where the disruption appears, and saw the water in considerable agitation, with much bubbling, and at short intervals it was thrown up in several places to the height of 3 or 4 feet. They saw no rupture in the earth, although they came within two or three rods of the spot, and state the water to have been two feet deep. About one o'clock on the morning of March 4th, Mr. Seth Sheldon and family, living one mile south from this spot, and being awake, were alarmed by a loud report from the north, by which their house and furniture were much shaken. They compared the sound, though louder by far than they had ever heard from this cause, to that of a cracking in the earth by frost in severe weather. Some others living rather nearer the spot, were awakened by the same report. That the rupture in the earth was made at that time is probable, though not certain.

It may be proper to state, that during the flood, no ice, except a few loose masses, was carried over, or near the spot where the disruption appears. This, therefore, could not have produced it.

Disruption of the Ground by Frost.

N. & S. S. Jocelyn Sc. N.H.

Fig. 1. is a transverse section, taken with a theodolite, from Deerfield river 28 rods south, crossing the longer axis of the disruption at right angles. The scale is 4 rods to an inch, although in laying off the heights and levels, the exact proportion was a little varied, to render the irregularities of surface more distinct. The letters of reference correspond to those on fig. 2, and need no explanation.

Fig. 2. is a bird's-eye view of the disruption and the adjoining region, very obligingly sketched by Mr. Derick Barnard of Troy, New-York. The surrounding country is somewhat contracted to bring more of it into view.

These are all the facts I am able at present to collect concerning this phenomenon. I have been particular as to the temperature of the air, and the situation of the adjacent country, from an idea that frost was a principal agent in producing it; and that, therefore, these circumstances would be important in fixing a theory. I will not, however, hazard any hypothesis on the subject; but if you deem the fact of sufficient importance, your opinion, Sir, is respectfully solicited.

Your humble Servant,

EDWARD HITCHCOCK.

Deerfield, Mass. March 26th, 1818.

Deerfield, June 3d, 1818.

Sir,

Since I sent you a description of a singular disruption in the earth in this town, another has been observed in the same meadows, about one mile from the former. This is less than the one of which I sent you an account, but its situation is almost exactly similar; it being on a small elevation, on the sides of which, at a few rods distant, is low wet ground. Indeed, the general description which I sent you will answer for this smaller disruption. The diameters of this last, are only 7 and 8 paces, and the curve is not perfect. There appears to have been an expansion of the earth's surface around both these spots, or disruptions, by which it was forced to give way at the point where there was the least resistance, which, of course, would be on the highest ground. The more I observe of this phenomenon, the more I am inclined to impute it to the agency of frost.

It may be proper to observe, that in neither of these disruptions has the general mass of the hills sunk in the least. Had this been the case, it might perhaps have accounted for them. It is also certain, that the soil below where it was frozen the past winter, has not been moved. I mentioned this fact in my first communication, though with some suggested doubt.

REMARKS.

An opinion having been requested by Mr. Hitchcock on the above facts, it may be observed, that there appears in the statement sufficient evidence that the phenomenon (as the author has suggested) is attributable to frost.

It is a fact, established equally by common experience and by numerous experiments, that water, in freezing, expands. It is generally estimated that 8 cubic inches of water, become 9 by the act of congealing. The expansion is attributed, with sufficient evidence, to a crystalline arrangement arising from a kind of polarity in the particles of water exerted when they are near congealing, by which they attract one another in certain points, and not in others. Dr. Black, with his usual felicity, has illustrated this tendency, by supposing a great number of small magnetized needles, thrust through corks, so that they will float parallel to the surface of water, to be thrown promiscuously into a vessel of that fluid. They will not remain in the situation in which they are thrown in, but, in consequence of their polarity, attractions and repulsions will be immediately exerted; they will rush together, with a force equal to the overcoming of a certain resistance; they will arrange themselves in pairs and groups, and finally, in a connected assemblage.

The particles of water attract each other with a prodigious force, when resistance is opposed; for it is well known that domestic utensils, trees, rocks, and even cannon, and bomb-shells, are burst with explosion, when water confined within them is frozen.

There is force enough then exerted by the expansion of freezing water, to produce all the mechanical violence, whose effects were so striking in the instance at Deerfield.

In the common cracking of the ground by frost, so extensively observed in cold climates, the effect appears to result in the following manner. The water contained in the ground, (that is, in that part which is within the reach of a freezing temperature) by congealing, expands and demands more space; a movement must necessarily take place in the direction where there is the least resistance; this will evidently be upward, because the atmosphere, the only counteracting power in this direction, cannot resist the expansion of the freezing water as much as it is resisted by the earth below the freezing stratum. Consequently, the freezing earth is forced upward, but being of unequal strength in different places, it cracks at the weakest spot; and the earth, for some distance on the sides of the fissure, is thrown into the position of two planes gently inclined, their relative position resembling that of a very flat roof, and the more they are lifted by frost, the more they will decline from one another, and the wider will be the fissure.

But why, in the instance which Mr. Hitchcock has related, did they overlap? The explanation appears to result from the circumstances of the case, as far as they can be understood without ocular inspection of the ground.

The elevated spot which cracked in so remarkable a manner, being nearly surrounded by a belt of low wet ground, the congelation of the water in this ground by the intense cold, would of course produce a very great expansive effort towards the elevated ground. This, not only on account of its elevation, but from its containing less water, would not be able to exert an equal counteracting effort. The surface of the ground, therefore, (without at all disturbing the unfrozen earth below,) was, by the expansive effort of the freezing water, pushed along towards the elevated spot. This spot being possessed of a certain power of resistance derived from its gravity, and from the freezing of the water in it, would not immediately give way; but the whole surface, it is probable, gradually rose for some time, while the expansion was going on and increasing. A cavity would thus be produced between that superficial layer of frozen ground which was rising, and the unfrozen ground below. This cavity would of course be filled with air derived from the atmosphere, and from the porousness of the ground below. When the place came to be overflowed, water would immediately rush in through any fissure, and this hydraulic and hydrostatic effort would force the air out at any orifice, and thus blow the water up with it. This was probably the cause of the agitation of the water, and of the bubbling of air, and of the throwing up of the water at intervals, observed by the boys on the 3d of March.

The effect of the water covering the ground, would be to weaken its cohesion derived from frost, and as there were probably hundreds of tons of pressure, the vaulted ground, when sufficiently weakened, gave way with a loud explosion and a violent concussion, as heard by Mr. Sheldon's family, a few hours after the facts observed by the boys. The parts of the arch now fallen in, (so to speak) necessarily either overlapped, or rose in ridges, piece being pressed against piece, as described and figured by Mr. Hitchcock.

We are indebted to this gentleman for his delineation of this singular case.

The freezing of water, and its attendant expansion, are productive of multiplied and very diversified phenomena upon our globe, whether we contemplate them in the delicate spiculæ of hoarfrost, the six-rayed stars of snow, or in the stupendous glaciers of the Alps, and the awful icebergs of Greenland.

Cambridge, January 25, 1819.

Professor Silliman.

Dear Sir,
If the following observations are worthy of a place in your valuable Journal, please to insert them, and oblige yours, with real esteem,

J. F. Dana.