CrEOLOGlOAL HISTOliY OF THE YELLOWSTONE 

 NATIONAL PAKK.* 



By Arnold Hague, 



U. S. Geological Siirreii. 



In the short time allotted to me 1 can only liope to present a brief 

 sketch of the main geological features of the country which you are 

 about to visit. JNIy remarks must, of necessity, be more or less iucom- 

 ]3lete, as my desire is uot so much to elucidate any special problem 

 connected with the many interesting geological questions to be found 

 here, but rather to offer such a general view of the region as will 

 enable you, during your live days' trip through the Park, to understand 

 clearly something of its physical geogra])hy and geology. 



The Yellowstone Park is situated in the extreme northwestern por- 

 lion of the Territory of Wyoming. Its boundaries, as determined by 

 the original act of Congress setting apart the Park, are very ill- 

 defined. At the time of the enactment of the law establishing this 

 national reservation, the region had been but little explored, and its 

 relation to the physical features of the adjacent country was but little 

 nnderstood. Since that time, surveys have shown that only a narrow 

 strip, about '2 miles in width, was situated in the Territory of Mon- 

 tana, but it was also found that a still narrower strip extended west- 

 ward into the Territory of Idaho. The question of ])roperly establish- 

 ing the boundaries, based upon our present knowledge of the ccmntry, 

 is now before Congress, and an act has already i)assed the Senate, pro- 

 posing to make the northern boundary coincide with the boundary 

 between Wyoming and Montana, and tlie western boundary coincide 

 with the Wyoming and Idaho line. The act under consideration 

 extends tlie soullu'rn Ixamdary of the Park to the 44th ])arallel of lati- 

 tude, carrying the area of the reservation scmthward 9S miles. The 

 eastern ])oundary is made to coincide Avith tlie meridian of 101)^ .'>0', 

 adding a strq) of country about 24^ miles in width along the entire 

 eastern side ol' Hie Park. 



The area ol" the Pai'k, as at present defined, is somewhat more than 

 .'],3(K) s(piiire miles, and the projiosed addition increases the I'eservation 



*' An address at. a special session of tlic Aiiu'iicni Institule of Miiuii<>' Engineers, 

 at Manimotb Hot Springs, Wyoiuiiig, on llic Ixmlcrs of tlu> National I'ark, July, 

 1887. (From Trans, yim. Inst. Minimi Enfiincrvi^.) 



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