232 Abbott: Concretionary Cellular Limestone of Durha7n. 



generally satisfied by inspecting the Cannon Ball bed at Roker, 

 but wonderful as this is it is greatly surpassed in interest by the 

 cellular structures seen in Fulwell, about a mile from it inland. 

 These beds are at least 100 feet thick and some two square 

 miles in extent, being evident on both sides of the river Wear. 

 The best beds are seen in F\ilwell Quarry, but they are being 

 taken away at such an enormous rate (some third of a million 

 tons annually), that in a few years they will be looked for there 

 in vain. 



x\ few theories have, it is true, been put forward from time 

 to time to explain the wonderful variety of the patterns seen in 

 the beds— these reach to several- hundreds — yet not one theory 

 has so far met with general acceptance. 



Recent work on the copper and tin alloys by Messrs. 

 Haycock and Neville has proved that in such dense things as. 

 bronzes the pattern forms and alters after they have becofne solids 



4^v 



; 'Honeycomb,' Specimens in the Four Stages. 



From all that I have seen during my long visits to Fulwell 

 since 1897 I feel satisfied the key to the solution of this difficult 

 problem lies in this direction, and I recognise that here segrega- 

 tion has gone a very long way beyond what geologists at 

 present think possible. 



We shall have in future to believe that some other force 

 than crystallization (we want a name for it) has led to the 

 development of its architecture in the form of rods, combs, 

 tubes, gridirons, etc. The force is undoubtedly connected with 

 the lime and not with the magnesia, the latter, however, acting' 

 as a very suitable matrix. 



Words fail me to describe the beauty, variety, and fossil- 

 like resemblance of the tons and tons of material to be met w^ith 

 in Fulwell- Quarry. 



The bed, as already hinted, is part of the Magnesian Lime- 

 stone (Permian) which occupies an important position in 



Naturalist^ 



