42 GEOLOGY OF THE HIGH PLATEAUS. 



meaning that none existed, we do find at the very summits unmistak- 

 able indications of the action of local and very small glaciers, with beauti- 

 fully preserved terminal morains. But I have never seen a morain in the 

 High Plateaus at a lower level than 8,500 feet, and 9,000 feet maybe con- 

 sidered as the mean level at which they are first encountered. We find 

 even these only on portions of flanks which bound the loftiest parts of the 

 tabular summits, showing that the loftiest parts alone accumulated ice and 

 generated small glaciers. This will not seem surprising even to those who 

 hold strongly pronounced views on the subject of the Glacial period if we 

 assume that during that period the plateaus stood considerably lower than 

 at present. That they did stand lower then is not improbable. We cannot 

 look to the Glacial period, therefore, for the discovery of any cause which 

 would retard the process of erosion ; but, on the contrary, we find in its 

 moister climate reasons for thinking that it may have been notably more 

 rapid than now.* 



I have discussed this subject at some length, because the age of these 

 faults is very important in the geology of the region, and is even more im- 

 portant to the southern and southwestern portions of the Plateau Province, 

 if possible, than to the High Plateaus. They are associated with the later 

 history of the canons and cliffs and with the climatal changes of the prov- 

 ince in the most intimate manner. The evolution of that region has long 

 since shown a tendency to cluster; it has even taken form; around certain 

 marked events of which one of the most prominent was the faulting, and 

 the consequences of these faults reach out in a manner which cannot be 

 appreciated until the whole region is described and the history of its con- 

 stituent parts delineated ; a work which I trust will be accomplished in the 

 near future. The} - everywhere betray in numberless ways their recency, 

 and I have presented only that evidence which strikes the eye at once where 

 we first encounter them. 



But while they are all comparatively recent some are older than others. 

 The two Kaibab faults in particular are apparently older than the rest, at 

 1> ast in part Those greater faults which cut through the heart of the 



' Whether erosion would proceed faster under the action of ice than of running water is a fjues- 

 tion which I do not raise. I 1 , has no present bearing. 



