206 



and the Ammonites planorhis, beds in the sections hitherto exposed 

 at Twerton, Weston, Saltford, and Willsbridge, and stating that 

 the Ammonites Bucklandi beds rest imconformably in these sec- 

 tions on the White Lias, in a note appended to page 495 

 notices this section as follows : — " In the railway cutting now in 

 course of excavation at Newbridge Hill, these representatives of the 

 Ostrea beds are present immediately above the Rhoetic series, but 

 are almost immediately overlain by othei's containing Ammonites 

 angulatus and A. BucUandi." Since the above note was made the 

 bank has been worked back for the purpose of obtaining the close- 

 grained White Lias stone for the new buildings at the station, and 

 greater facilities afforded for the examination of these beds. 



The cutting extends in a N.W and S.E. direction, and has 

 exposed the series of beds from a thin representative of the bone 

 bed, (about one foot below the rails,) through the superincumbent 

 dark shales, with intervening hard light-blue or gray marly bands, 

 onwards through the Gotham Marble at the base of the White Lias, 

 and upwards through the latter formation and the Ammonites 

 angulatus beds to the dark-blue clays of the Bucklandi or Lima 

 series. The beds at the N.W. end of the cutting are nearly 

 horizontal, and rest conformably one on the other, but the red beds 

 of the Keuper marls are brought up by a fault at this end, and a 

 series of small dislocations which affect the whole section from the 

 Lower Lias on the top to the Rhoetic clays below, bringing 

 down the beds by a series of steps, continue throughout to the 

 S.E., where they obtain their maximum development in a consider- 

 able fault, which causes the White Lias to rapidly disappear below 

 the level of the metals. On the N.W. side of this fault the top bed 

 (the " Sun bed" of William Smith) dips at an angle of from 5" to 

 8®, S E., and has a downthrow of 8 feet by two vertical steps. On 

 the S.E. side, where it appears again in a projecting shoulder, the 

 dip is 20'', S.E., the vertical dislocation of the top bed at this point 

 being 15 feet. From the point where the top White Lias bed 

 is last seen dipping rapidly downwards to the point where it 

 appears again on the opposite side is a width of 55ft. This fault 

 is traceable right across the line to the opposite banks on the S., 

 where, owing to the rapid slope of the hill, the beds are only partly 



