120 



BULLETIN OF THE ESSEX INSTITUTE. 



Potsdam sandstone and Manitou limestone, which have 

 such a prominent development north of Ruxton Creek, 

 are wholly wanting south of this line, the throw of the 

 Ute fault south of the Ruxton fault being great enough 

 to conceal all the sedimentary formations below the 

 Fountain series. The Ruxton fault not only breaks 

 and displaces the Ute fault, but south of the former the 

 latter has a greatly increased southwest hade (inclination 

 to the vertical). 



Immediately east of the bridge over Ruxton Creek and 



Granit 





\ 



Hade \ 



\ 





Avenue the railroad passes through a tunnel about one 

 hundred feet long, which with the open cuts at either end 

 gives a continuous section of nearly four hundred feet. 

 The western end of this section shows a red and gray 

 mottled and banded sandstone, which, although non- 

 glauconitic or nearly so and closely resembling the sand- 

 stones of the dikes, must be correlated with the Potsdam. 

 The prevailing dip of this sandstone is southwest 60°- 

 80° ; but it is highly disturbed, crushed, and mineralized 



