1382.] ^1^ [Frazer. 



^Yery compact dark blue slale S. 30^ E.-3CO. 



Same, with N. W. dip for a short distance. 



Same. Dip E. 30° S.-26^. 



Same. Dip N. 30° W.-240 (iu ravine 300 ft. wide). 



Same. Dip E. 15^ S.- ± 30O. 



Same. Much intersecting quartz. 



Same. Dip ± S. E. ± 40°. 



Same. Dip ± S. 35° E.-250. 



Sandy slate, weathered nacreous scliist E. 30^ 8.-20°. 



Iron ore clays. 

 L Limestone, with traces of fossils. 



The horizontal distance covered by group A is 4341 feet, and bj^ group 

 B, 6060 feet. 



It will not be easy to construct an inversion with these dips. It cannot 

 be denied that f/iis Mountain Creek rock lies on chlorite and hydro-micas, 

 and, if there be uo fault, according to Mr. Hall's theory, the fossiliferons 

 limestone should lie about 3000 feet below these schists. 



At 1029 feet east of the bridge the Mountain Creek rock, still dipping 

 E. 25° S.-250, is replaced by hydro-mica schist as it tcere by the gradual 

 dying out of the fragments of quartz. The dip in the first part of these 

 measures, which assumes the entirely changed form, is E. 30° 8.-32°. 

 This goes on alternating with quartzite and chlorite schists for 2700 feet, 

 when a Mountain Creek rock comes in lying unconformably against the 

 preceding. A repetition of the Mountain Creek rock commences from 

 here, which is about 100 feet west of the first house* [*in 1876] of the set- 

 tlement on the Maryland side of the river, opposite Harper's Ferry. 



Chlorites, hydro-micas and quartzites therefore clearly lie above and iu 

 contact with the Potsdam if this be its representative. 



(3.) "But it is equally clear that the mica schists and (jueisses are not 

 found between the Primal and the rocks of the third belt." 



This is, perhaps, equally clear with Proposition 2, but no more so. 



As incidentally mentioned above, the whole structure of the east flank 

 of the South mountain is opposed to this view. Here the schists lie on the 

 central kernel or axis which, whether it be Laurentian or Huronian is, 

 without doubt, older than the rocks we are discussing. 



In Section 9, of Report CC, small synclinals of Potsdam are seen rest- 

 ing on the schists. In Section 7 of CC, four miles S. E. of Mt. Holly, the 

 Potsdam (?) quartzite is seen overlying and underlying the chlorite slates. 



At Chikis a belt of schists underlies the upper Potsdam quartzite and 

 overlies the lower quartzite. 



If the quartz rock of Peter's creek be the Potsdam, it lies on chlorite 

 schists. So do the detached masses of Potsdam quartzite of North Co- 

 dorus, Spring Garden, and Mauheim townships in York. 



The same is true of the Potsdam between Doe run and Toughkenamon, 

 and in other places in South Chester and in Sadsburj-, E. and W. Brandy- 



