A bittern's croak

July 22.

Start just before 8 A.M. and sail to the Falls of Concord River. We are early enough to see the light reflected from the sides of the gyrating water-bugs.

Heard from a bittern, a peculiar hoarse, grating note, lazily uttered as it flew over the meadows. A bittern's croak: a sound perfectly becoming the bird, as far as possible from music.

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For the last mile above the Falls the river becomes rocky, the rocks gradually increasing in number, until at the Falls its bed is crowded with them. Some of the rocks are curiously water-worn.

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These are just above the Fordway. There are two pleasant old houses near the Fordway on the east side. 

I was surprised to see on the upright sides of these rocks, one or two feet above the present  water, very distinct white spots, looking like white paint across the river. Examining, I found them to be three fourths to one inch in diameter of an oval or circular form; the white coating spreading on to the rock in an irregular fringe like the feet of an insect, increasing their resemblance to a bug, and they were raised one eighth or one tenth of an inch and finely dotted with the contained ova, reminding me of coins, — shaped like bugs or coins, — and I at first bent to read the inscriptions as if they were a work of art. They were full of ova with much water in them or other liquid.

The shores at the Falls are firm and rocky, though for the most part covered densely with bushes, — maples, alders, grape-vines, cat-briars, etc. There is no space for the river to expand in, and it is withal very much contracted in capacity by the rocks in it. Its bed is more or less strewn with rocks for some sixty rods, the largest forming rocky isles with soil and bushes and trees on them, though only some five or maybe six (?) feet high. 

There is water six and a half feet deep between the Fordway and the narrowest place below. 

I was surprised to see on the rocks, densely covering them, though only in the midst of the fall, where was the swiftest water, a regular seaweed, growing just like rock-weed and of the same olive-green color, — "Podostemon Ceratophyum, River-weed," — still in bloom, though chiefly gone to seed. Gray says it is " attached to loose stones," and Torrey says it "adheres to pebbles," but here it covered the rocks under water in the swiftest place only, and was partly uncovered by the fall of the water. 

I found, in what I gathered, a little pout which had taken refuge in it. Though the botanist, in obedience to his rules, puts it among phaenogamous plants, I should not hesitate to associate it with the rockweed. It is the rockweed of our river. I have never seen it else where in the river, though possibly it grows at the factory or other swift places. 

It seemed as if our river had there for a moment anticipated the sea, suffered a sea-change, mimicked the great ocean stream. I did not see it a few rods above or below, where the water is more sluggish. So far as I know, then, it grows only in the swiftest water, and there is only one place, and that the Falls, in Concord River where it can grow. 

Gray only speaks of it as growing at " the bottom of shallow streams," Torrey says "at the bottom of shallow pebbly streams," and Bigelow only says it is attached to stones at the bottom. 

Yet apparently our sluggish river is only a stream, and sufficiently like ordinary rippling streams to admit of its growth at this one spot. A careless observer might confound it with the rockweed of the sea. It covers the rocks in exactly the same manner, and when I tore it off, it brought more or less of the thin, scaly surface of the rocks with it. It is a foretaste of the sea. 

It is very interesting and remarkable that at this one point we have in our river a plant which so perfectly represents the rockweed of the seashore. This is from four to eight or nine inches long. It has the peculiar strong fresh-water scent. 

The west end of Hill's Bridge is (upper side of planking) eight feet eleven inches above summer level, under side of string-piece seven feet eight inches. I cannot hear that it ever rises on to this bridge, but there is a good deal of fresh drift stuff on the top of the abutment under the string-piece at seven feet eight inches above summer level, apparently washed on in the spring. The upper side of planking at east end is about nine feet eight inches above summer level.

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It is remarkable how the river, even from its very source to its mouth, runs with great bends or zigzags regularly recurring and including many smaller ones, first northerly, then northeasterly, growing more and more simple and direct as it descends, like a tree; as if a mighty current had once filled the valley of the river, and meandered in it according to the same law that this small stream does in its own meadows. 

A river of this character can hardly be said to fall at all: it rather runs over the extremity of its trough, being filled to overflowing. Its only fall at present (above the Falls and this side Framingham) is like the fall produced by a dam, the dam being in this case the bottom in a shallow. 

If, after flowing twenty miles, all the water has got to rise as high as it was when it started, or rather if it has got to pass over a bottom which is as high as that was where it started, it cannot be said to have gained anything or have fallen at all. It has not got down to a lower level. You do not produce a fall in the channel or bottom of a trough by cutting a notch in its edge. The bottom may lose as much as the surface gains. 

Rocks which are covered by freshets a week or more will have lichens on them, as that on my old plan just below the Hemlocks. 

If our river had been dry a thousand years, it would be difficult to guess even where its channel had been without a spirit level. I should expect to find water- worn stones and a few muddy pools and small swamps.

H. D. Thoreau, Journal, July 22, 1859

A bittern's croak. See September 20, 1855 (“The great bittern, as it flies off from near the railroad bridge. . . utters a low hoarse kwa kwa”); September 25, 1855 ("Scare up the usual great bittern above the railroad bridge, whose hoarse qua qua, as it flies heavily off, a pickerel-fisher on the bank imitates.”)