FIG. IV. 



Cross Section or Profile of Graduated Diggings (as 

 of range G, in Fig. II.) Scale 20 feet to inch. 



EXPLANATIONS. 



a, a, Surface of ground (and overlay of next range 

 to be uncovered.) 



d, d, Former extension of surface, now removed. 



m, Overlying earth, here 7 feet thick. 



n, Marl, 8 feet thick. 



5, s, s, Green-sand earth. 



G, The bed of marl, here removed from its original 

 height, the dotted line next above G i, to the line 

 below and the lower part, w, t, still to be remo- 

 ved, to the bottom, at s. 



i, Small drain, to intercept and lead off the springs 

 coming out of m. 



t, Lowest graded side, or drain, to receive and dis- 

 charge accidental floods into the stream. 



o, Wall of marl, left to be last dug out, to keep out 

 the water and earth from 



g, p, k, Successive fillings of previous excavations, by 

 the overlay removed from the next uncovered. 



(345) 



