Very little thought or attention is paid to the insidious¹ changes produced by water on the Earth’s surface.  
Not a day passes, or has gone by, but that a large quantity of material is transferred from one locality to another. Every shower carries from some higher point to a lower, and a certain amount of drift goes toward some ocean. Small streams contribute to the larger ones, and all lead to the great ocean reservoirs. In going across our country many important evidences are to be seen of the immensity of work accomplished² by water, in the removal of vast areas and depths of land.
 
One of the most noticeable and apparent seen by the writer is in the valley of the Rio Grande, in passing through New Mexico and at some other points. For more than 100 miles through[89] this valley in the spring and summer you seem to be following an ordinary creek³ that gives little idea of the importance attached to such a stream as the Rio del Norte. You see a stream, only thirty or forty feet wide, with steep, abrupt⁴ banks, of a sort of adobe⁵ soil, some six to ten feet high.
 
At various places, if you observe, in the bends of the stream these perpendicular⁶ banks of earth will be caved off into the water, at frequent intervals⁷. When the next annual freshet comes this loosened earth is carried away toward the Gulf⁸ of Mexico, and portions of it reach there while other parts will be lodged⁹ at different points on the way.
 
Now this visible, and natural process, has been going on for ages, and the effect of this incessant¹⁰ work and stupendous result is to be seen far as the eye can reach for hundred of miles.
 
Here follow the proofs of this long and diligent¹¹ labor¹². In all directions you see hills, or immense mounds¹³ of land, like inverted¹⁴ deep pans, with flat bottoms, of all sizes, so that their flat tops would include from one acre to hundreds. These mounds all have quite precipitous sides, subject to the wash of every rainy season. As you study the character of these high mounds you will soon be convinced they are not upheavals¹⁵, as their[90] tops in all directions seem to have a common level. Among these mounds will be occasional ones that have been washed away to a point, and here and there one reduced to half its original height. These hill-tops, if they may be so called, were beyond doubt, at some very remote time in the past, the common level of the country for hundreds of miles, and as they will average 100 feet high or more, it is beyond the power of conjecture¹⁶ to estimate the time required to wash all the vast area away that once existed to make up the level of this valley.
 
Another similar exhibition is at and near River Falls, in Wisconsin, a town on the east bank of the Mississippi, some thirty miles east of St. Paul. Here the same occurrence seems to have taken place, of a washing away of the greatest bulk of the land, and leaving similar mounds with their flat tops, on many of which are quite extensive farms, approached by very precipitous roads at some favorable point on their sides. These mounds seem to have different strata¹⁷ of soft rock, on which they stand, the lowest and thickest of gray sandstone, quite soft, and must, with the others, be gradually wasting away by frosts, and other agencies to disintegrate¹⁸. Only one yellowish stratum¹⁹ is strong enough to be used for some building purposes.
 
[91]While there are hundreds of these mounds that must have once been the level of the w............