THE RIDGWAY FAULT. 63 



little work entitled " Barnes' Guide to Dorchester," which is now 

 out of print and difficult to obtain. The description of the section 

 is copied in Damon's " Geology of "Weymouth " at page 24. Mr. 

 Osmond Fisher, on sending me the pamphlet last week, suggested 

 that the section should be printed afresh in our " Proceedings," and 

 this proposal, I think, we ought to follow. He says : " The 

 singularity of the section consists in a portion of the Oxford clay 

 making its appearance between the Wealden Beds, and where the 

 fault cuts off the chalk." The writer, having opportunities of 

 watching the progress of the works, was aware of an Oolitic clay 

 appearing here so long ago as 1846 when the trial shafts were dug. 

 He then found a piece of a shell of a Trigonia in the clay from 

 the shaft ; but when the cutting commenced Gryphea dilatata 

 occurred in plenty, with portions of other fossils of the Oxford 

 clay, and he was convinced of the identity of it. Experienced 

 geologists, however, to whom he communicated the fact would 

 scarcely credit the tale ; but at last they were convinced by 

 personal inspection on the spot. Mr. Fisher suggests the following 

 solution to account for this curious phenomenon : " The Oxford 

 clay Avas, at the time of- the fault, in a more ductile state than the 

 intervening and more shaly Kimmeridge clay, and when the general 

 subsidence took place, which occasioned the fault, it may have been 

 squeezed up past the ends of the broken strata into the position 

 which it now occupies." 



So AYeston, in his paper on the "Geology of Ridgway, near 

 Weymouth," in the Quarterly Journal of the Geological Society for 

 1848, says " The subterranean result of this state of things [i.e., 

 elevation and subsidence] would be the fracture of the Oxford 

 Oolitic stratum and great pressure on the subjacent Oxford clay. 

 This would force up the Oxford clay from beneath through the 

 opening thus made, that is through the very place where we find it 

 between the chalk wall and the overturned upper surface of 

 Hastings sands." 



Weston shews that the Oxford clay at Ridgway is clearly not 

 the Oxford clay stratum in its natural position, but a part of it 



