POST-PALEOZOIC UPLIFTS. 315 



inference from the exposures he saw; for, although my interpretation is 

 based upon evidence accessible also to him upon his trip, it would have been 

 impossible for him to appreciate its import without much detailed study in 

 the surrounding region. He hit upon the correct age of the Capitol granite, 

 but did not get the clew to the structure of the "Shinbone," although he 

 knew and correctly plotted the course of the later uplift to which it belongs, 

 and determined the age of the same dynamic action, as elsewhere observed 

 by him. These granites are marked or clad with their own. waste in most 

 exposures, but there are some good contacts with strata under which they 

 have protruded. A very good example occurs in Slaughter Mountain west 

 of the pass through which the track goes between Fairland and Granite sta- 

 tions, on the Austin and Northwestern Railroad. 1 know of no superposition 

 of Carboniferous rocks upon the sediments covering this magma; but wherever 

 the Cretaceous overlies it, directly or otherwise, it seems to have no dip con- 

 formity with it, as do the earlier strata when they appear in contact with this 

 granite. 



B. THE CRETACEOUS UPLIFT. 



There remains one prominent line of upheaval which proves in two ways 

 its title to be designated the youngest orographic trend: (1) It cuts the other 

 trends without itself losing continuity in any exposures, and (2) it involves 

 the Lower Cretaceous Beds as well as the older strata. 



The course of the axes of this uplift is nearly north 50 degrees east.* That 

 it has greatly increased the confusion of structure need not be stated, but 

 there are some features of its distribution and of the late topography which 

 tend to simplify problems which might otherwise be made more obscure. In 

 the Cretaceous area, and in less degree upon the Paleozoic fringes of our dis- 

 trict, the effects of the northeast upheaval are easily studied, although at times 

 sections may be found in which it is very difficult to explain the present topog- 

 raphy upon any theory which seems to agree well with a majority of the facts. 

 I have sometimes been so puzzled by obstinate exposures of this nature that 

 the whole fabric of the geologic history of the region as now outlined has 

 seemed at variance with any possible interpretation of the Cretaceous and later 

 record. But gradually, after months of study and most careful plotting of 

 the observations, some of the facts which appeared most contrary have at last 

 become among the strongest evidence in support of the geognostic scheme 

 promulgated herein. 



Mr. Hill has been very positive that the Cretaceous sea covered the whole 

 of the Central Paleozoic area, of which our district is but a part. I am un- 



*North 41 degrees east, magnetic; declination, 9 degrees 15 minutes east; corrected, north 

 50 degrees 15 minutes east. 



