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<ul><li><p>UTAH SULPHUR BEDS 429</p><p>THE RECESSION OF NIAGARA FALLS.Probably no one who has looked down on the falls of the Niagara</p><p>River and the grand canyon they have carved for themselves out ofthe solid rock but has felt his brain oppressed with the idea of eternityand the incomprehensibility of it. It is a thought that will be drivenhome to those who may read the recent pamphlet of Mr. G. K. Gilbert ofthe United States Geological Survey concerning the rate of recession ofNiagara Falls. Not only does he tell us that the great falls are notwhat they have been within the memory of man, and show us picturesand maps to prove that their outline has changed, but he gets out histape line and measures the distance that they have receded withincertain years.The data for computing the rate of recession of Niagara Falls include</p><p>surveys of the crest line made in 1842, 1875; 1886, 1890, and 1895,and cameralucida sketches made in 1827. During the period coveredby these data the rate of recession has not differed to an importantextent from the natural conditions. The present and prospective diver-sions of water for economic uses interfere with the course of natureand may be expected to modify the rate of recession.The rate of recession of "the Horseshoe Fall, or the rate of lengthening</p><p>of the Niagara gorge, during the sixty-three years from 1S42 to 1905is found to be five feet per annum, - with an uncertainty of one foot.For the thirty-three years from 1842 to 1875 the rate was apparentlyslowerthan for the thirty years from 1875 to 1905. The rate of reces-sion of the American Fall during the seventy-eight years from 1827 to1905 was less than three inches per annum.The time consumed in the recession of the falls from the escarpment</p><p>at Lewiston to their present position, or the age of the river, is not hereestimated.- It can not properly be computed without taking account ofall conditions, local and temporary, affecting the rate of recession, andsome of those conditions have varied greatly from point to point andfrom time to time.Mr. Gilberts report is published as Bulletin No. 306 of the Geological</p><p>Survey. It is accompanied by a report on the survey of the crest lineof Niagara Falls by Mr. W. Carvel Hall, who made the survey in June,1905. The work was done under a plan of cooperation between theSurvey and Mr. Henry A. Van Alstyne, State engineer of New York.Mr. Hall adds two tables to his report, one showing the artificialmonuments and other permanent reference points connected with thetriangulation of the surveys, the other the distance between permanentreference points.</p><p>COVE CREEK SULPHUR BEDS, UTAH.</p><p>A glimpse of Hades itselfand what is worsethe smell of itmaybe obtained at Sulphurdale, Utah, where sulphur . is apparently inprocess of formation and concentration. Here and at several otherlocalities in the neighborhood are valuable deposits of sulphur, which</p></li></ul>


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