GEOLOGICAL SURVEY OF THE TERRITORIES. 35 



rials. The cong^lomerates prevail, but there will be found interstratifled 

 seams or local beds of several feet in thickuess, of a fine white-yellow 

 or brick-red voloauic dust aud ashes, so that wheu these beds are 

 eroded the surface around presents the appearance of the ground ' 

 about an old furnace. I know of no district where there is a better 

 opportunity to study the great varieties of volcanic action in past 

 geological times than in the range of mountains which separates the 

 Gallatin Valley -from the Yellowstone. On the west side of the valley, 

 from the Lower Canon to the Second Canon, a distance of at least thirty 

 miles, the indications of ancient volcanic action are most remarkable 

 and varied in their character. The erosive forces have cut deep canons 

 into the sides of these mountains, 2,500 to 3,000 feet through the con- 

 glomerates, and have worn the portions remaining into the most won- 

 derful architectural forms. Domes, pyramids, pinnacles, palaces, 

 indeed almost any form which one could conceive, can be seen here. 

 One gorge was called the Palace Canon on account of the symmetrical 

 palace-like forms which could be seen everywhere. The sides of these 

 gorges are vertical walls, inaccessible, except in a few localities, to man 

 or beast. One can stand in the bed of a little stream and look up the 

 vertical walls on either side 2,500 or 3,000 feet. Such gorges as these, 

 extending from five to twenty miles oftentimes, are very numerous. 

 Literally hundreds of them may be found in these ranges extending up 

 to the very crest or water-divide, carved out of the solid mass of con- 

 glomerate or trachyte. There is certainly no limit to the remarkable 

 scenery which the artist could select in this prolific field. 



Cropping out here and therein the bottom of these deep gorges may be 

 seen the older sedimentary strata, as the Carbonil'erous limestones, and 

 even those of later date, as the Jurassic, Cretaceous, or Tertiary. The 

 general dip of the unchanged strata is about northeast, and in the valley 

 of Trail Creek the sandstones and clays of the Brown-Coal period may 

 be seen passing beneath the huge mountains of volcanic conglomerate. 

 Farther south and west the limestones appear, and the metamorphic 

 rocks are not seen to any extent until we enter the West Gallatin 

 Canon. We are thus enabled to gain a pretty clear idea of the original 

 shape of this valley, that it was really marked out in the process of 

 upheaval. I will remark here that I shall attempt to show hereafter 

 that the streams, in coming out of their channels, did not follow any 

 preformed chasms or fissures, but quite the reverse. Most of the canons 

 were formed by the streams cutting their way directly through the 

 ridges, at right angles to the axis of upheaval. 



As I have previously remarked, the granitic rocks are mostly confined 

 to the main ridge of mountains on the east side of the valley, but in the 

 valleys of the smaller streams that flow into the Yellowstone from the 

 west side just below the Second Canon, as Eock Creek and Canon Creek, 

 the metamorphic rocks are largely exposed. The Second Canon is com- 

 posed of metamorphic rocks entirely. Scattered over the surface of the 

 valley below are many huge bowlders of granite, which could not have 

 been transported to their present position by any forces now in operation. 

 It is quite evident that all the forces, whatever they may have been, 

 operated from above down the valley. Ui)on the foot-hills, and in one 

 instance on the top of the basaltic floor, several hundred feet above the 

 present bed of the river, are huge rounded bowlders, 25 to 50 feet in 

 diameter, which must have been transported either from the canons of 

 those little streams above mentioned or from the Second Canon, a dis- 

 tance of ten to fifteen miles. 1 know of no power except the combined 

 action of water and ice that could have brought about these results. A 



