358 University of California Publications in Geology [Vol.13 



cross-bedding would have to be laid down sharply abutting the under- 

 lying beds. In all forms of cross-bedding known, however, the bed- 

 ding grades into the contact below along curves. In figure 46 cross- 

 bedding of coarse quartzite has been cut obliquely and a thin stratum 

 of medium-grained quartzite has been laid down. Above this, cross- 

 bedding of coarse material was again developed. The whole has been 

 truncated and very coarse grits deposited. This case is similar to 

 that described above but repeated several times; but in addition we 

 have another important piece of evidence. It is a matter of actual 

 field observation that cross-bedding is always concave upward, and 

 here we find the bedding curving in agreement with the upper side as 

 determined from other data. 7 



Z.J7.-.T. - Very Coarse 



a b 



Fig. 4. Bedding in Saragossa quartzite showing order of succession. 



Above the gritty schists and quartzite there is a series of soft 

 biotite and muscovite schists and above these are very heavy-bedded 

 quartzites, which, however, contain occasional strata of schist. Con- 

 tinuing to the southwest, the dip of the rocks flattens somewhat, and 

 at Gold Mountain the quartzite dips 8° to the northeast. This upper 

 portion is nearly all heavily bedded and largely sacchroidal. As esti- 

 mated from this section the thickness of the quartzite is about 3500 

 feet (fig. 5), but since the upper limit is unknown the total thickness 

 may be much greater. 



The quartzite extends northward to Burnt Flat and to the south- 

 east beyond Cienaga Seca and Broom Flat, Although well exposed 

 in many places, over a considerable area it is found only as fragments, 

 due to its brittle nature and the rounded topography. Over a large 

 part of the country the soil is sufficient to support a heavy growth of 

 timber, but usually the fragments of quartzite are so abundant as to 

 leave little doubt as to the nature of the underlying rock. 



i Cf. Lawson, Andrew C, The Archean geology of Bainy Lake re-studied, 

 Mem. Geol. Surv. Canada, vol. 40 (1913), pp. 62-63. 



