Licence: Public Domain Mark
Credit: Tableaux of New Orleans / by Bennet Dowler. Source: Wellcome Collection.
Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)
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![I;-. Harvy Elkins bored to the depth of two hundred and seven feet. Thirty feet below the surface, fragments of Indian pottery were brought up, and part of a deer's horn, recent shells, and bones of land animals, were occasionally raised. The stratum in which the boring was stop- pod consisted of a hard, blue silicious clay. Brackish water, with volumes of some kind of gas, arose. {Interior Valley, North America, i, 76.) A respectable member of the New Orleans bar informed me that a planter of undoubted veracity, on Berwick's Bay, thirty miles from the Gulf, near Franklin, having had a very large live oak, supposed to be the oldest in the country, which stood on the water's edge, and fearing it might fall suddenly, he cut it down. It proved to be hollow. He found under the roots of the tree, burnt wood, where a fire had once been made under the centre, and anterior to the growth of this ancient tree. A physician of New Orleans states, that in an attempt to get water near Lake Pontchartrain, by boring about 100 feet, pieces of cypress stumps, or wood, were brought up at intervals, together with fragments of pottery, as pipes; these have been often found in digging at various depths and places near New Orleans. In digging wells, cypress stumps are met with of great size, presenting difficulties in the operator's way. This is the first subter- teranean forest, and is from three to six feet deep, more or less, and is chiefly cypress, which appears to be most a durable kind of wood when submerged, or covered with earth. Had these subterranean stumps been sudddenly and deeply covered by deposits and drifted alluvion, &C., examples of which may be seen in the river bank, (where the old levee has been abraded and anew, natural one made in the rear, in a single season) not only the stumps, but a portion of the shafts of the trees, would have been found erect, and covered. The lateral abrasion of the river bank during high water of the Mississippi, in many placi well as upon the shore opposite the Second Municipality of New Orleans, below the town of Gretna, exposes, as if by a vertical section, the stumps of enormous cypress trees, numerous cypress kni gcthor with the stems of sh nibs, standing erect exactly where they grew, on a horizontal line or com- mon level. This range, which is seen during the low stage of the river, corresponds nearly < l i i iresent low water mark ; it is found where the bank or natural levee is old, and upon thai side i ivrv where there is more or less lateral abrasion, or no considerable accretion by recent deposits. These indications, together with largo growing trees, particularly live oak, immediati 1\ bank, will guide the observer in his examinations. In fact, live oaks of large size on 0] .-ides of the river, near the banks, are reliable witnesses, showing that the river has not cb for many centuries. Thus it is easy to see that the river channel between Gretna and Ln I has not changed materially for ages. It will be proper to offer a few remarks in this place relating to the rapid alluvial actions which are, and have been, going forward within the limits of New Orleans, inasmuch as many ] regard these actions as harbingers of such a change in the river channel as will leave the city and the ii\ er distant from each other—a groundless fear, because the river at low water is but a few inches above the level of the sea; its current is, probably, in a great degree owing to the force from behind, (vis a tcrgo,) acquired by gravity, or the falling down this inclined plane of regions more elevated. All that part of the volume of the water (more than two hundred feet) below the level of the sea, must be inoperative as a vertical abrading force, without which a new chan- nel cannot be dug out. Hence, the largest crevasses fail to make a deep channel, or any channel at all; for as soon as the water falls through the levee, it is nearly on a level with the sea. and hence can have but a trifling vertical power. The force of a column of water depends wholly on its altitudo, not on its width. The lower Mississippi can change its bed only by slow lateral abrasion such as is now progressing in New Orleans. Many causes may contribute to accelerate lateral abrasions and deposits —an examination of which will show how these sudden, local, and sometimes very great changes may expose or cover cypress stumps upon the shores of the river. At the upper border of the Second Municipality, a protruding land-point, fortified by wharves and lined with ships, directs the current towards the opposite shore at McDonough and Algiers, below which a still more salient point causes a rebound of the current towards the lower part of the First, and the whole of the Third Municipalities. Eddies exist in front of much of the Se- cond Municipality. The angles of incidence with which the currents strike Algiers and the](https://iiif.wellcomecollection.org/image/b21115680_0013.jp2/full/800%2C/0/default.jpg)
