190 



PROCEEDINGS OE THE GEOLOGICAL SOCIETY. 



[Jan. 8, 



sometimes only a foot or two, at other times 50 or more feet in 

 thickness, made up of blocks of foreign rocks, heaped together in 

 the "wildest confusion, and cemented by a sandy or calcareous ma- 

 trix containing Oolitic fossils. One of the best illustrations of the 

 remarkable alternation of these beds of such very different character 

 is afforded by the section at the opening of the romantic gorge of 

 the Allt-gharashtiemore (Gartymore Burn) near the village of Port 

 Gower (see fig. 16). 



Occasionally, where the laminated beds have been deposited on 

 the irregular surface formed by the top of one of the " brecciated 

 beds," we see what interference has been produced by the projecting 

 masses of the latter with the usually regular stratification of the 

 former ; but as soon as these projections were covered up and 

 masked in clay, the even lamination of the beds is found to be as re- 

 gular as before. 



§ 2. Age of the "Brecciated beds." 



The investing matrix of the blocks yields many fossils, generally 

 (as is also the case with those of the equivalent strata which are not 

 " brecciated ") fragmentary and waterworn. The short and thick 

 Belemnites, and the coarse massive Ostrece have often resisted the 

 forces which have comminuted the other shells. Large masses of 

 waterworn coral, with numerous fragments of wood, also occur in 

 the midst of the heterogeneous assemblage of foreign blocks. The 

 finely laminated beds which alternate with the " brecciated beds," 

 however, yield many fossils in an admirable state of preservation ; so 

 that we are at no loss in fixing the age of the beds, which is that 

 of the Upper Oolite. The following fossils are those which most 

 frequently occur in the " brecciated " and associated beds between 

 Garty and the Ord : — 



Fossils from the matrix of the " Brecciated beds " of the Ord Sfc. 



Plesiosaurus (vertebras). 



Fish-remains. 



Belemnites abbreviatus, Mill. 



(fragments). 



Ammonites mutabilis, Sow. 



- alternans, Von Buck. 



Eudoxus, IP Orb. 



■ ■ biplex, Sow. 



Ceritliium, sp. 

 Turbo, sp. 

 Nerita ? 



Lima concentrica, Sow., sp. 



Pecten, sp. 



Ostrea Roemeri, Quenst. 



solitaria, Sow. 



expansa, Sow. 



Rhynckonella Sutherlandi, Dav. 

 Rhynckonella, sp. 

 Spines of Cidaris and Acrosalenia. 

 Isastraea oblonga, Edw. 8? Haime. 

 Leaves (Cycads, Conifers, and Ferns). 

 Trunks of Conifers and Cycads. 



§ 3. The Matrix of the " Brecciated beds." 



The material which invests and encloses the foreign blocks in 

 these singular strata, varies considerably in character. Usually it is 

 more or less calcareous ; but often it is arenaceous, and sometimes 

 argillaceous. Not unfrequently the whole mass of the rock, matrix 

 and included blocks alike, is found traversed by numerous cracks, 

 which are filled with Calc-spar. The great disturbing forces which 



