Jasper County Democrat, Volume 13, Number 25, Rensselaer, Jasper County, 6 July 1910 — ASTONISHING POWER of RUNNING WATER [ARTICLE+ILLUSTRATION]

ASTONISHING POWER of RUNNING WATER

'<&' GEOPGE EREDEPICK WEIGHT AM,IX-D-)

<r z HE power of running water Tto remove sand, gravel and pebbles increases in a remarkable degree with the increase in velocity, so v that mining engineers cah m make accurate calcula--31 tlons concerning the re■Lfll ■ locity which is necessary to remove stones of a certain size from their sluiceways. The transporting power increases 64 times with each doubling of the velocity; so that if you increase the velocity threefold you have increased the transporting power of the water 729 times and if you quadruple it you have increased the weight of the pebble,' which it would move 4,096 times. This at first thought seems incredible, but it is nevertheless true, and prepares us to appreciate the astonishing results that are produced by running water. Water moving three feet in a second, or a mile in six hours, will carry along with it particles of fine clay and keep them in suspension. Water moving at twice that velocity will lift and r-arrv along with it fine sand; while a velocity four times as great will sweep along fine gravel and water moving at the rate of two miles an hour will carry along stones as big as a hen’s egg. There is hardly any limit to the size of a pebble that would be rolled along by a current Of six or eight miles an hour, blocks as big as houses being sometimes set in motion and transported for considerable distances. In various ways one can obtain positive evidence of this power of water transportation. If, for instance, he attempts to wade across the Platte river in Nebraska, which is overloaded with sand and has a gradient of seven or eight feet to the mile, and hence a very rapid current, he will find his bare legs stung by the particles of sand and fine gravel that are 'driven against them. Or If after a storm one pauses to listen he will hear what sounds Tike distant cannonading, produced by the knocking of the stones together as they are rolled along upon the bottom of the stream.

the st rearn cr o s ses this range. with a gradient that is continuous with that of the vast prairie regions above and below. The Yenisei river has cut a similar gorge across the gr a nit e mountain chain which rose up to

separate the fertile plains of Minusinsk from the vaster plains of . northern Siberia. Coming to our own country, we have in addition to the streams already mentioned, gorges and canons on a most impressive scale in the upper part of the Susquehanna river, where the east branch cuts across the Allegheny mountains south of the state of New York, and forms the beautiful Wyoming valley, which is wholly one of erosion. The west branch has likewise cut a gorge of equal dimensions 50 miles or more tn length west of Williamsport, which is fully 1,000 feet in depth, as one can see by the fact that here the coal mines on either side are that distance above the bed of the stream and of the railroad track. Coming to the

The erosive power of a stream flowing over a rocky bed is determined by its ability to shove along sand and pebbles and gravel over its bottom. It is these particles of solid matter that accomplish the eroslpn, acting as a rasp, or sandpaper, or more properly a sand blast, to remove the solid rock beneath and deepen the channel of a stream. In order to do this, however, there has to be proper adjustment between the supply of loose solid matter to be transported and the volume and velocity of the water. If there is more sand and gravel than the current can handle, this will accumulate upon the bottomland fill up father thandeepen the bed. If there is too little material the stream will flow oven the rocks without effecting much erosion, while if there is just the right amount of solid matter to be shoved along it will deepen the channel with great rapidity.

There are many striking examples of the work which has been accom plished by rivers in deepening and widening their channels. We look upon the rise of mountain chains as being most majestic illustrations of the power of natural forces, but the fact is equally Impressive that in many cases rivers which run across the line of mountain elevation are able to wear down their channels as fast as the mountains rise and thus maintain their ancient onward course. The Hudson river has thus sawed down & channel through the solid rocks which in ancient geologic times arose across Its course at West Point and below, all that picturesque valley of the Hudson being a valley of erosion. The Delaware river has worn an even more striking gorge through the Blue Ridge at the Delaware Water Gap, where it cuts directly across the very hard strata of Medina sandstone constituting Blue Ridge, forming perpendicular walls on either side 1,000 feet In height. Similar gorges are found in the Susquehanna and Potomac and many other rivers along the Appalachian chain just above where they emerge upon the surrounding lowland. We often speak of such rivers as "bursting” through their barrier. But there was no bursting in the operation. These gorges were cut by the slow' process which we have described, the rivers lowering their channels gradually as the mountains slowly rose Sfcross them. Among the most striking examples of rivers which have by erosion kept pace with the elevation of mountains across their course Is that of the Colombia river’ In Oregon, where for a long distance it occupies a trough running directly through the mountain chain thousands of feet in depth. Another very striking Instance is that to be seen tn the Amnr river where i it crosses the Bureya mountains in eastern Siberia. For nearly 100 miles ... tit

other side of the Allegheny mountains, one strikes into the various branches of the Ohio river and finds himself in a trench several hundred feet below the general level of the lapd, and extending for more than 1,000 miles in length until the river emerges into the center of the Mississippi valley. The upper part of the Mississippi occupies a similar gorge for a still greater distance. Everywhere along this portion of their course on ascending either side of the rivers to the summit, one will find himself upon a vast plain, extending off in either direction, whose main superficial irregularities are those which have been produced by the erosion of the countless smaller streams which joined together make the great rivers.