274 GEOLOGY AND MINING INDUSTRY OF LEADVILLE. 



probably somewhat diminished. The Iowa glacier, on the other hand, seems 

 to be contracting' as it descends, and in the plcne of this section the dis- 

 tance between the crests of its bonnding moraine ridges is onlj" a little over 

 one thousand feet. Here the outline of the Lake beds shows a bay in the 

 ancient lake Arkansas and that the older Iowa glacier occupied a wider bed 

 than the later one. Except at the foot of the Prospect Mountain, the beds 

 lie in an almost horizontal position. 



Section N. — In Scctiou N the teaching of the Lake beds is still more 

 suggestive. The moraine material of the Evans glacier, which was probably 

 again united into one sheet, is spread out over a still wider surface; while the 

 reconstructed outline of the Arkansas lake shows that from Graham Park 

 across to Georgia gulch a ridge then extended, through which the present 

 bed of California gulch has been carved out since the Glacial epoch. 



Section o. — In ScctionO, which runs through Fryer and Carbonate 

 Hills, only the top of the latter and a portion of what is now California 

 gulch probably remained above water during the Glacial epoch. 



Section P. — In Sectiou P, which runs across the mesa country. Lake 

 beds and Wash cover the whole surface as far as the ridge north of the mouth 

 of the Arkansas. The underlying beds are represented as lying in a single 

 broad syncline, since, while there may probably be minor undulations, as 

 in the sections above, there naturally can be no data for determining their 

 position. 



As regards underground structure the transverse sections are mainly 

 useful as showing probable depths at which the ore-bearing horizon may be 

 found. They are too nearly parallel to the direction of major strike, which 

 is that of the majority of the folds, to give a correct idea of these folds ; and 

 their intersection with fault planes, being also at an acute angle, presents a 

 somewhat distorted angle of dip. Still it may be observed that on these 

 north and south lines the beds have a tendency to form anticlinal and syn- 

 clinal folds. Bearing in mind that the prevailing direction of strike is in 

 a northwest direction, the continuation of the folds will be found a little 

 farther to the north in each successive section; for instance, in Section J 

 the fold under Ball Mountain finds its normal continuation in Section K at 



