« PředchozíPokračovat »
GEOGRAPHY AND NATURAL HISTORY.
The District of Columbia, as originally ceded to the Federal Government, by the States of Virginia and Maryland, contained ten miles square, or one hundred square miles; but when, in 1846, Alexandria was retroceded to Virginia, the area of the District was reduced to about sixty square miles. The Capitol lies in 38° 52' 20"north latitude, and 77° 0' 15" west longitude from Greenwich. The Observatory, from which the American meridian is computed, lies in 38° 53' 39".25 north latitude, and 77° 2' 48" (5 hours, 8 minutes, 11.2 seconds) west longitude.
The District of Columbia is bounded by the State of Maryland on the east, north, and west, and by the Potomac river and Virginia on the south. The distances from the seat of government, of some of the principal cities in the Union, are as follows :
Miles ..700 .1,000 .1,200 ..226 .136 .120 .850
CAPTAIN JOHN SMITH'S DESCRIPTION
“There is but one entrance by sea into this country, and that is at the mouth of a very goodly bay, eighteen or twenty miles broad. The cape on the south is called Cape Henry, in honor of our most noble Prince. * The north cape is called Cape Charles, in honor of the worthy Duke of York. The island before it, Smith's Island, by the name of the discoverer.
This bay lyeth north and south, in which the water floweth near 200 miles, and has a channel for 140 miles; of depth, between six and fifteen fathoms, holding a breadth, for the most part, ten or fourteen miles. From the head of the bay to the northwest, the land is mountainous, and so in a manner from thence by a southwest line, so that the more southward, the farther off from the bay are those mountains; from which fall certain brooks, which, after, come to fine navigable rivers. These run from the northwest into the southeast, and so into the west side of the bay, where the fall of every river is within twenty or fifteen miles one of the other. The mountains are of divers nature, for, at the head of the bay, the rocks are of a composition like mill-stones ; some of marble, &c., and many pieces like bristol, we found as thrown down by the water from those mountains ; for in Winter they are covered with much snow, and, when it dissolves, the water falls with such violence that it causes great inundation in some narrow valleys, which is scarce perceived, being once in the river. These waters wash from the rocks such glistening tinctures, that the ground in some places seemeth as gilded, where both the rocks and the earth are so splendid to behold that better inducement than ours might have been persuaded they contain more than probabilities. The vesture of the earth in most places doth manifestly prove the nature of the soil to be lusty and very rich.
In Summer, no place affordeth more plenty of sturgeon; nor, in Winter, more abundance of fowl in the time of frost. I took once fifty-two sturgeon at a draught, at another sixty-eight. From the latter part of May till the end of June are taken few, and they are but a yard long. From then, till the middle of September, they are seldom less than two yards long; and in four or five hours, with one net, there were ordinarily taken seven or eight. In the small rivers there are, all the year, plenty of small fish; so that, with hooks, those that would take pains have sufficient.
Such great and well proportioned men are seldom seen, for they seem like giants to the English, yea, and to their neighbors, yet seemed of an honest and simple disposition, and, with much ado, restrained from adoring us as God.”
Washington and Georgetown, and, indeed, the whole District, is underlaid with gneiss rock, the trend of which is nearly east and west. Throughout the City of Washington and its suburbs the rock is covered to a greater or less depth with a tertiary formation of mineral matter, a considerable part of which is drift. The drift in some places consists of sandstone, limestone, jasper rock, quartz in boulders, pebbles, gravel, sand, clay, and loam. The mixture of loam and clay often abounds in a peculiar state of aggregation, as if the clay and loam had been at first separate, and in masses of considerable size, and
ly thrown into a DISTRICT OF COLUMBY
confused mass. Such is the character of the ground on En
glish Hill, on East Branch, just below the Navy Yard, about the brick kilns, between the Navy Yard and the arsenal.
This character of the tertiary is well adapted to the manufacture of brick, and constitutes the basis of this manufacture in Washington. The parts A, A, A, in the sketch, represent the gneiss rock, which was originally compact and, apparently, durable, and, as found in the neighborhood of Little Falls, some two miles above Georgetown, it is extensively quarried, and used in cellar and foundation walls, and other coarse work. It splits in two directions nearly at right angles to each other, which fits it for faced work with little labor. There is one peculiarity in this rock, however, which renders it very uncertain as a durable stone. In certain locations it goes to decay rapidly, and disintegrates entirely in a few years. The rock, as it exists on the Virginia shore of the Potomac at Little Falls, has so broken down along the road side that a rod may be forced
into it in some places for two feet from the surface, by the thrust of the arm. It is not so throughout, but only in certain localities. The cause of this peculiarity has not been investigated. It is proper to say, with regard to the underlying gneiss rock of the Potomac valley, that the rock does not appear at the surface at all the places marked A; but, from the appearance and features of the surface, it is evidently there; and it contributes to make and shape the contour of the surface. To the eastward and northeastward, the valley of the East Branch constitutes a flat river bottom which receives the drain from the contiguous banks and lands. As we proceed along the east side of the Potomac, from the Capitol toward the north and northwest, the rock first makes its appearance parallel with the river (that is, the trend or line of the ridge of the rocks), in the vicinity of Pennsylvania Avenue where it crosses Rock Creek, which forms the dividing line between Washington and Georgetown.
Georgetown lies virtually at the head of tide-water, although the salt water does not ascend nearer than forty or fifty miles. Georgetown, therefore, is at the junction of the tertiary and primary rocks, and at the last fall of the river, before it plunges into positive tide-water. Georgetown may be said to rest on the primary gneiss, while Washington, though evidently resting on the same base, has its substratum so low, by the dip of the rock beneath the surface, that it may be properly, and is generally, called tertiary, on account of the accumulation of clays, sands, and drift that have been piled upon it to the depth of many hundred feet, and which belong to the deposits of the tertiary formation. No considerable borings in the way of artesian wells have been made, so as to