DAVIS: THE GRAND CANYON OF THE COLORADO. 153 



Button maintained the antecedent origin of the Colorado drainage sys- 

 tem, trunk and branch. It is very probable that these geologists might 

 now modify in some degree the statements that they made thirty and 

 twenty years ago as to the indifference of the streams, especially of the 

 smaller streams, to the displacements of the plateau region. Other 

 origins may be suggested for several of these waterways. 



The Smaller Streams of the Grand Canyon District. — Cataract creek 

 (called Cascade river by Newberry, pp. 62, 66, and Coanini creek by 

 Powell, a, p. 197) follows in a general way the gentle northward dip of 

 the strata that it dissects, and may well be classified as a consequent 

 stream, revived with every uplift. A possibly consequent origin for 

 that part of Virgin river which passes between the two parts of the 

 Hurricane fault has been suggested above. The Little Colorado fol- 

 lows a monoclinal belt of relatively weak Permian and lower Triassic 

 strata for a hundred miles, and in this part of its course it may be 

 plausibly regarded as a subsequent stream ; such was certainly its habit 

 where we crossed it in the Permian belt on the Flagstaff-Tuba road ; 

 but for forty miles northwest from this point to its junction with the 

 larger river, it runs obliquely against the gentle structural slope of the 

 Marble platform and enters the main canyon just east of the Kaibab 

 monoclines, a highly significant fact which will be referred to further 

 on. Paria creek has, according to the geological maps of the district 

 (Dutton, c, Atlas, sheets II., XXI., XXII.), an anticlinal course in its 

 upper, and a monoclinal course in its lower part. Although the lower 

 part is now deeply incised in resistant Triassic strata on the northeast 

 border of the Paria plateau, its position there may have been gained by 

 headward growth along the once-overlying weak strata of the gently 

 dipping monocline during a lower stand of the land ; for the stream 

 seems to be accordant with the strike of the beds. The upper part of 

 the Paria drains the denuded district in which the Kaibab arch fades 

 away to the north (Dutton, a, pp. 253, 297); the lateral branches of 

 the stream are here to all appearances normal obssquent streams, 

 whose length increased as the denuded area widened ; the trunk stream 

 is merely the axial member of the obsequent group, longer than the 

 laterals because the dip of the strata to the north is gentler than to the 

 east and west. The whole length of the creek may therefore be reason- 

 ably explained as an example of spontaneous adjustment of drainage to 

 structure, and not as of antecedent origin. House-rock valley is un- 

 questionably subsequent, as has been implied already on page 124, and 

 as will be more fully considered below. Kanab creek has every appear- 



vol. xxxviii. — no. 4 4 



