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33 inches; evaporation will reduce it to 44 inches, when fully exposed to the sun and air. One season of extreme drouth would, upon the expanse of these lakes, produce an extreme depression, while the contrary would have the effect of producing a corresponding rise. It cannot be a matter of so much. astonishment that such expanded areas of water, subject to such influences, should be greatly effected; the wonder is, that they do not oftener present greater fluctuations than they do, the equal and almost unvarying stage at which we find them, is due to the uniformity of the seasons, and the systematic order in which nature is conducted in all her works.

The semi-annual alternations observable in summer and winter, arise from other and well known causes. In summer, the supply is unchecked, and the consequence is, an increase to the height of 30 inches, or thereabouts; when in winter, these supplies are again checked, a consequent depression follows. Measurements to ascertain exactly these semi-annual fluctuations, have never been thought necessary. Besides, it is not uncommon for ice, in large bodies, to collect at the outlets of the lakes, and, for the time, prevent the usual discharge, and a lower stage of water, is the consequence, than otherwise would be. When this occurs in the chain of lakes, as it frequently does at the outlet of Lake Huron, in connection with a west wind, as in 1824 and 1831, it diminished the depth of the Detroit river, opposite the city, to over ten feet, widening the beach more than twenty rods, and making it practicable, (except in the immediate channel,) to cross without danger, on foot, from the American side to Isle au Cochons or Hog Island; and a further proportional decrease took place in lakes Erie and Ontario, while the pent-up water flowed back into lakes Huron and Michigan. For these reasons, and the want of uniformity in the temperature of the winter months, the minimum height is not to be depended upon.

Besides all this, the effect of winds sometimes acts in favor, as well as against the other irregularities. The geographical position of the lakes is such, as that, allowing them to prevail from the same point, at the same time over them all, (which is, by no means, always the case,) they produce a variety of results. A west wind forces the water of Lake Erie into the Niagara river, at the same time, the waters from the foot of lakes Huron and Michigan are forced into the straits of Mackinac, and these again are met by the waters of Lake Superior, through the straits of Ste Marie. Hence the straits which connect lakes Huron and Erie, have all the indications of a tide, though irregular as to time, as well as to the amount of its elevation and depression, and it has often both rose and fell in about the same proportion, and sometimes in the same period, as the lunar tides in those rivers which empty into the

ocean. But whenever these tides take place, either in the lakes themselves or in the straits connecting them, they are fortuitous, and are the results of accidental disorder, common throughout the lake region.

Another feature may be observed of the lakes, different in nothing from the ground swell of the ocean-the reaction of the water, after having been pressed by the wind for a few days or hours in one direction.

Vol. I.

The most favorable points for noticing this reaction, is at an inlet or bay; Lake Superior, which has the largest surface, presents the most marked traits. Here, while the explorations by the geological corps were in progress, the past season, at the mouth of Grand Marrais river, which empties into a bay one mile wide and two miles long, having an outlet of a quarter of a mile wide into the lake, was observed the returning waters from the west, in wide undulations. The effect upon the smooth surface of the bay was a gentle elevation, which arose to one foot or more for a period of fifteen minutes, then subsiding, again returned at equal intervals of time, until the lake, after a lapse of a few hours, resumed its natural level.

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Table of elevation and depression in the waters of the Lakes, compared with that of June 1, 1839.

January
April
May

66

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30, 25.j

9,

19.

October 1.

61

12,
29,

November 10,

13,1 20,

1841. January

21,

December 10,
21,
1,

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66

Increase,
Decrease,

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Height of water,....

Increase,

66

66

66

66

Decrease,

66

DETAIL OF THE ELEVATION AND DEPRESSION FOR 1340.

....

....

Rain and wind from N. E., fluctuations 15 to 18 in...
Same,.....

....

Wind west, season dry and hot,........
Light showers, weather same as last observation,
Much rain in June and July, on Lake Superior,...............
Season dry, little rain,..

Wind west, river fell suddenly,

Heavy rain last 24 hours,..

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Moderate, do

Increase,

....

Decrease, Freezing, wind moderate from west,...
Increase, Ice made in river in considerable quantities,
Decrease, River blocked up by ice, no wind,....
River nearly closed, wind moderate from west.....

........

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MARSHES-their origin-once inhabited by the Beavers—their enlargement and diminution-other causes of their production -without timber-their uses-marl-peat-rich soil-cause of the subsidence of the water on them-instances of their becoming dry-causes still in operation-irreclaimable marshes.

It is perhaps a matter of less difficulty than is generally supposed, to account for the existence of most of the marshes that so abound in this and other portions of the west. We may consider them as level tracts, so continuous often as to be but little broken for many miles, and which expand, or become narrow as the base of the hills and higher grounds, approach or recede; while the latter seem to stand as distinct and sharply defined as islands, whose shores are fringed by a line of timber, and whose foliage waves over the tall grass beneath, and which borders the very margin of this timbered belt, at times receding like deep indented bays, and again projecting in detached islands, and peninsula points, not unlike the meanders of an actual arm of the sea or lake-the level grassy surface being substituted for their waters.

Most of the marshes, however extensive, were once the habitation of the beaver, and were nothing more than expanded and shallow lakes of water. The stream that is now found universally to flow through them, was anciently at a lower level, which is sufficiently indicated when the depth of vegetable mould is penetrated and the former surface exposed. This depth is found to vary from one to many feet.

From the well known habits of the beaver, we may suppose their first labor was to raise a dam sufficiently high to protect them from attacks by land, and as the bottoms of the lakes became filled up by the decay of grass and roots, an adtitional elevation of the dam became necessary, and this gave a greater arca to the lakes, which continuing to spread, the adjacent land whose relative level could be but little above the ordinary banks of the stream, was overflowed, leaving those islands, bays, and peninsula points we have alluded to, to give an indescribable beauty to the landscape.

A process of enlargement or diminution of the marshes, is constantly going on according as the original cause is either operating or has ceased; the latter is the case within, and to a great extent around, the neighborhood of permanent settlements. The beaver is nowhere to be found, excepting at the sources of Thunder bay river, and some other minor streams, on the lower peninsula; but Mr. Burt informs me that he found them within twelve miles of the coast north of Mackinac, in considerable numbers, where they had newly inundated the country to the depth of several feet.

Another cause of the stoppage of the streams, is the falling

of timber across them, which becomes permanently fixed by the superincumbent pressure of the waters.

A long series of years, if not ages, must have elapsed to produce the filling up of these ponds by the decayed vegetation, and the destruction of so large a body of timber as that which once covered the ground they occupy, little or no vestige of these forests remaining, even of a fossiliferous character.

The benefit of these marshes to the country, consists not altogether in their picturesque and verdant appearance, or in the rural charm with which nature clothes them, so far from being practically useless, they, in great measure have, to this day, been the pasture grounds of the domestic herds, which otherwise could not have been supplied in the first settlement of the country. Their first use has been to sustain, by their spontaneous crops, the dependent husbandman, placing him beyond the care and labor of opening new fields for his supplies.

Another value, which will hereafter be better known and appreciated, is derivable from the immense beds of marl, so universally found in them; with its uses, as a cement and manure, thousands are already acquainted. It is well known to be peculiarly adapted to our soil as a manure, and its quantity is inexhaustible.

Another characteristic production of the marshes, is the peat with which they abound; this may in future be found useful as a fuel, and may supply the place of that article when other sources are exhausted.

Nor need I here announce, what is so well known, (and which results from the fact of the composition of the soil, being made up wholly of decayed vegetation,) their surpassing richness, or that when, by artificial drains, or otherwise, they have been made arable, the experiment of planting and sowing for years, has attested them the most valuable and enduring lands in the state. So much is this the case, that their acquisition by those who understand them best, is more eagerly sought for than the richest of the woodland.

Numbers have yearly become dry, so as to be brought under cultivation, which have heretofore been known only as wet meadows, and where their yielding oozy muck could with difficulty be made to support the weight of a man, they have now no other water upon them than the original stream, and that no longer spreading over the whole surface as formerly, but confined to its proper channel.

The causes which will ultimately have a tendency to drain the great portion of them, is slow in its operations, but nevertheless, is sure. The operation may be expedited by artificial means; either, by straightening the usual serpentine course of the streams, or by enlarging their outlets, or which is the most effectual method, by removing the embankment, or beaver dam.

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