Tuesday, January 30, 2018

Measuring the depth of Gowing's Swamp



January 30. 

P. M. – To Gowing's Swamp. 

I thought it would be a good time to rake in the mud of that central pool, and see what animal or vegetable life might be there, now that it is frozen. I supposed that tortoises and frogs might be buried in the mud. 

The pool, where there is nothing but water and sphagnum to be seen and where you cannot go in the summer, is about two rods long and one and a half wide, with that large-seeded sedge in a border a rod wide about it. Only a third of this (on one side) appears as water now, the rest a level bed of green sphagnum frozen with the water, though rising three or four inches above the general level here and there. 

I cut a hole through the ice, about three inches thick, in what alone appeared to be water, and, after raking out some sphagnum, found that I could not fairly reach the mud and tortoises, – if there are any there, — though my rake was five feet and nine inches long; but with the sphagnum I raked up several kinds of bugs, or insects. 

I then cut a hole through the frozen sphagnum nearer the middle of the pool, though I supposed it would be a mere mass of sphagnum with comparatively little water, and more mud nearer the surface. To my surprise, I found clear water under this crust of sphagnum to about five feet in depth, but still I could not reach the mud with my rake through the more decayed sphagnum beneath.

I returned to the thicket and cut a maple about eighteen feet long. This dropped down five or six feet, and then, with a very slight pressure, I put it down the whole length. I then went to the thicket again, searched a long while for a suitable pole, and at last cut another maple thirty feet long and between four and five inches thick at the butt, sharpened and trimmed and carried it on my shoulder to the spot, and, rough as it was, it went down with very little pressure as much as twenty feet, and with a little more pressure twenty-six feet and one inch; and there I left it, for I had measured it first. If the top had not been so small that it bent in my hands, I could probably have forced it much further. 

I suspect that the depth of mud and water under where I walk in summer on the water andromeda, Andromeda Polifolia, Kalmia glauca, sphagnum, etc., is about the same. The whole swamp would flow off down an inclined plane. 

Of course there is room enough for frogs and turtles, safe from frost. 

I noticed that the sap flowed very freely from one of the maples which I cut. 

In the meanwhile the hole which I had first cut had skimmed over. I stooped to look at the ice-crystals. The thin skimming, which did not yet cover the whole surface, was minutely marked with feathers, as in the frost on windows in the morning. The crystallization was, as usual, in deep furrows, some a third of an inch wide and finely grained or channelled longitudinally. These commonly intersected each other so as to form triangles of various sizes, and it was remarkable that there was an elevated space between the sides of the triangles, which in some cases was not yet frozen, while you could see and feel the furrow where the crystals had shot on each side much lower. The water crystallizes in certain planes only. 

It seems, then, that sphagnum will grow on the surface of water five feet deep!

What means the maple sap flowing in pleasant days in midwinter, when you must wait so late in the spring for it, in warmer weather? It is a very encouraging sign of life now.

H. D. Thoreau, Journal, January 30, 1858

I supposed that tortoises and frogs might be buried in the mud. See November 23, 1857 ("Garfield, who was working in what was Moore's Swamp, tells me that he sometimes digs up frogs in the winter, when ditching in springy places, one at a time."); December 13, 1857 ("Apparently many [tortoises] winter in the mud of these ponds and pond-holes.")

The pool, where there is nothing but water and sphagnum to be seen and where you cannot go in the summer, is about two rods long and one and a half wide. See November 23, 1857 ("I looked down over the large open space with its navel pool in the centre."); See May 31, 1857 (“That central meadow and pool in Gowing's Swamp is its very navel,”); August 23, 1854 ("There is in the middle an open pool, twenty or thirty feet in diameter,. . .an abrupt edge next the water, this on a dense bed of quaking sphagnum, in which I sink eighteen inches in water, upheld by its matted roots, where I fear to break through. On this the spatulate sundew abounds.”). See also February 1, 1858 ("When the surface of a swamp shakes for a rod around you, you may conclude that it is a network of roots two or three feet thick resting on water or a very thin mud. The surface of that swamp, composed in great part of sphagnum, is really floating.")

What means the maple sap flowing in pleasant days in midwinter, when you must wait so late in the spring for it. See March 14, 1856 ("Tapped several white maples with my knife, but find no sap flowing; but, just above Pinxter Swamp, one red maple limb was moistened by sap trickling along the bark.")

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