104 Annuersary Address. 



the trap, the metamorphism is so great that, in hand speci- 

 mens it is often difficult to say whether the rock is trap or 

 sandstone, limestone or shale, owing to the transference 

 through the masses, both of aqueous and of igneous origin, 

 of various mineral constituents of either, whilst the trap was 

 in a molten state and the adjoining strata expanded by the 

 influence of its heat. At some distance further on the 

 change eifected is not so great, and the beds of sandstone, 

 &c., can be distinctly traced back to the place where their 

 characters become blended with those of the trap. This is 

 perhaps one of the best localities in Britain for the study of 

 metamorphic phenomena, such an extensive area of rock 

 being clearly exposed. 



Proceeding onwards to Budle Bay, the well known Posi- 

 donia shales were examined with much interest. These 

 shales, of a reddish brown colour, abounding in the shells of 

 the fragile Posidonia, associated with the remains of a few 

 land plants, have evidently been deposited in the still brack- 

 ish waters of an ancient lagoon or estuary, little disturbed by 

 tidal action. 



Above these lie the superficial deposits of gravel and sand. 

 The gravel consists chiefly of pebbles derived from rocks at 

 various distances to westward, well rounded by littoral ac- 

 tion ; together with several of a bright red limestone, which 

 does not appear to have been seen in situ within the district, 

 and which some imagine to have been transported from 

 Scandinavia, where a similar limestone is found. It seems 

 more probable, however, that a red limestone occurs in the 

 immediate vicinity, the geological position of which is a little 

 above the Posidonia shales, the red hue being the result of 

 metamorphism caused by the trap rocks in the neighbour- 

 hood. 



The party returned by way of Spindleston crags to Bam- 

 burgh, where upwards of fifty dined in the tent. After 

 dinner a long and most interesting paper, illustrated by 

 numerous drawings, was read by Mr George Tate, " On the 

 pre-historic Sculptured Stones of Northumberland and the 



