IXXXU PKOCEEDINGS OF THE GEOLOGICAL SOC1ETT. [May I9OO, 



yet, in a thick mass of Kimeridge Clay, at the depth of 1397 feet. 

 At Brabourne there are some 250 feet of the Upper division (chiefly 

 Kimeridge Clay, but with a little Portlandian). At Ottinge and at 

 Dover this division also occurs. 



The Middle Jurassic division reaches farther northward, to 

 Chatham, where Oxford Clay next underlies the Lower Greensand. 

 At Brabourne both Corallian and OxfordiaD occur, with a total 

 thickness of nearly 550 feet, at Bopersole about 300 feet of those 

 formations, and they are also found at Dover ; but we have no sign 

 of them yet farther westward or northward than the places named. 

 Southward, in the Sub-Wealden boring, more than 220 feet of beds 

 above the Oxford Clay have been classed as Corallian. 



The Lower Jurassic division has a still wider range, occurring in 

 two of the London borings (Meux's and Streatham) as well as at 

 Richmond. North of London all the evidence we have is that of 

 absence, as also at Crossness, on the east ; but the trial-borings for 

 coal at Brabourne, at Ropersole, and near Dover prove the existence 

 of Lower Jurassic beds farther east, to the thickness of 189, 164, 

 and 156 feet respectively. 



We see then that, in every boring in which Jurassic beds have 

 been found, the Lower division is represented wherever the borings 

 are deep enough to reach it, and that the same is the case for the 

 Middle division in every boring that has pierced through the Upper. 

 On the other hand, there is one case (Chatham) where the Upper 

 division is absent, the Middle occurring next beneath Lower Green- 

 sand, and there are three cases where the Lower division alone is 

 present, next beneath the Gault, in and near London. Further, in 

 one only of the London borings north of the Thames, and that the 

 most southerly (Meux's), are Jurassic beds of any sort present 

 on that side of the river, all the borings farther north that go deep 

 enough showing nothing between the Cretaceous and very much older 

 rocks. 



This successive northerly thinning of the Upper, Middle, and Lower 

 Jurassic divisions seems to point to the connexion of the underground 

 Jurassic beds with masses farther south, and not with those of the 

 northern outcrop. But what may happen west of Richmond we 

 know not. 



The Lias and the Trias. 



Of that thick and mostly clayey formation the Lias, no sure sign 

 was forthcoming until the Brabourne boring some two years ago 



