nick's ckeek ikon oke kec^ion. 



35 



Mountain. Staley's Creek whei'e it enters Marion is about tAvo thousand feet a1)0A e 

 the sea. 



G B O L O G Y — S T R U C T U R E. 



The rocks of the Pond Mountain Eange he in saddle form, and the saddle appears 

 to sink towards the east from the highest part of the mountain, near the western end 

 of the Iron Region. At the IS'ick's Creek Gap a small basin may be perceived upon 

 the top of the saddle, and the small southern saddle of the basin may rise eastward 

 so as to replace the other that is sinking ; or on the other hand this southern saddle 

 may be only a small roll that soon dies out eastward as well as westward. The rocks 

 of Brushy Mountain form in like manner a saddle, but it appears to have at the western- 

 most end of the region a double crest, the northern part being the larger ; but the 

 southern part seems to rise eastward and to unite with the northern before reaching 

 the eastern end of the region ; that is, the small basin at the top of the saddle disap- 

 pears eastward. There are probably more saddles than one just north of Pond 

 Mountain. Between the Pond Mountain and Brushy Mountain saddles the rocks 

 lie in basin form of course ; and there is another basin just north of Pond Mountain. 



The dips of the Brushy Mountain saddle are, in the western half of the region, 

 forty-five degrees southerly on the south, and sixty to eighty or even ninety degrees 

 northerly on the north ; and appear to grow rather less steep towards the east on the 

 north side, and to steepen in that direction on the south side. The dips of the Pond 

 Mountain saddle are forty-five degrees on either side at ISTick's Creek, but steeper 

 westward, especially on the northern side, so as to become in the Thomas tract 

 seventy degrees southerly, reversed. 



ROCKS. 



The rocks of the region are almost wholly sandrocks and shales ; and seem to be- 

 long Avholly or chiefly to the Formation called in Pennsylvania and Virginia 'No, 

 I, corresponding to the lower part of the Lower Silurian System. They are grey at 

 the bottom, brown in the middle and red at the top. On the top of Brushy JVIoun- 

 tain, near the southwest corner of the Henderlite tract, near the middle of the saddle 

 and consequently among the lowest rocks exposed in the region, are clifis of a pud- 

 ding rock made up of rounded pebbles as large as peas and smaller, of white and 

 rosy translucent quartz, apparently in part if not wholly water- worn crystals. Just 

 north of the region and just south of it the blue lime rock of Formation II (also 

 Lower Silurian) appears ; and it is likewise found in smaller patches within the 

 region in the middle of some of the basins, probably in all the deep portions of the 

 basins. Between the layers of the lime rock, at least near the bottom, appear to be 

 layers of brown sand rock. 



