102 



AN AMERICAN GEOLOGICAL RAILWAY GUIDE. (PA.) 



113. Trap dikes to the south and west, across the river. 



114. The "White Spot" high on the mountain to the east is supposed to be a remnant of Pots- 

 dam sandstone left lying unconformably on Laurentian. 



115. A noble fault crosses the river three times in the gap; once at the canal locks, again at the 

 rock at the west mouth of the old tunnel and then runs vertically up the steep. Hudson River slates 

 dipping 10 south abut against the bottom plate of Oneida standing vertically. Between this and 



Auburn very fine exposures of Clinton red shales. No fossil ore. 



116. Back of this on the south side of Summer Hill, multitudes of Hamilton and Portage fossils. 



117. Centre of the soft anthracite collieries. Fine geological headquarters. For four miles 

 before reaching this place the whole Devonian and Bermcian systems stand vertical, affording a 

 section of 20,000 feet of rock, up to the top of the lower productive coal series in the fold of the 

 great synclinal in the lower part of the town. View from the top of Sharp Mountain, 800 feet high, 

 instructive. Hotel at Mount Carbon close to where Lea's footprint was found. 



118. Road runs along the base of the Laurentian Mountains, over calciferous, holding limonite 

 beds. 



119. Cornwall Magnetic Iron Mines 6 miles to the south; holds copper, trap and marble. 



120. Iron mines, limonite, south of the town. 



121. In the gap opposite the town five ribs of Pottsville conglomerate enclose the four lowest 

 anthracite coal beds. A cross section of the coal measures up to the 12th bed can be made here. 



122. Remarkable large fossil tree stems visible in the coal measures here. Glacial striag cross 

 white pebbles in the conglomerate crest of mountain west of the Ashland Gap, opposite Mt. Carmel. 



123. Large collieries. Shaft sunk by diamond drill. 



124. Little Schuylkill here makes a cross section of the Pottsville coal basin. 



125. From here down to Port Clinton the Little Schuylkill cuts through ten anticlinals. 



126. All along here the thinness of the Trias upon the Cambro-Silurian is revealed by erosion. 



127. Famous old limonite mine. 



