GO REPORT — 1842. 



Dr Stark offered the following explanation : — As each mass of ice tumbled over 

 the rocky precipice it was dashed into a thousand pieces, in fact, resolved into the 

 irregular crystalline particles of which it was composed. The melting of ihe surface, 

 &c. saturates this granular mass with water, and so soon as any portion of it gets be- 

 yond the disturbing influence of the falling masses, the low temperature of the ice, 

 combined perhaps with the pressure of the overlying loose material, tends to solidify 

 a portion, and thus forms a new layer. As the fall of the ice over the precipice is not 

 a continuous but an interrupted process, each layer has time to acquire a certain 

 amount of thickness and solidity, before another mass, by the concussion it occasions, 

 disturbs the process, and by its additional weight causes the whole mass to move 

 forwards. Dr. Stark thought that the depth and distance to which the concussion 

 reached, and the weight of the overlying materials, would cause the layers to form 

 at a dip of 70°. Every layer was therefore formed originally at this angle or dip, and 

 parallel to each other; but as they advanced forwards in consequence of the success- 

 ive falls of ice, and the formation of new layers behind them, they were seen to lose 

 their parallelism to each other, and lie at lower and lower angles at every step of ad- 

 vancement towards the termination of the glacier. 



Dr. Stark accounted for this by showing, that the melting of the base, which was 

 necessarily greater at the termination of the glacier than where the layers were first 

 formed, gave the whole mass a tendency to fall forwards from the want of the sup- 

 port before and below, a tendency which was increased by the greater amount of 

 friction at the base of the layers retarding the motion of that portion, whilst the 

 forward motion aided still further their falling forwards, as there was no friction 

 on the upper surface to oppose the retardation of the friction at their base. The 

 plastic nature of the whole mass, and the transversely stratified structure, he 

 thought would allow of this change of parallelism and of dip being accomplished 

 with facility. 



Dr. Stark, in conclusion, remarked, that a glacier may, and probably in most cases 

 does exhibit during its course all the chief forms of stratification described above. At 

 its origin in the upper valleys the strata are horizontal. A little lower down the 

 horizontal strata occupy only the middle portions of the glacier, whilst the longitu- 

 dinal and vertical compose its breadth. Still lower down the vertical layers are alone 

 apparent; and at the lower extremity of the glacier, if the original structure has 

 been broken up and destroyed from any cause, the transverse stratification is alone 

 apparent. 



On the Discovery of the Remains of Fishes at the base of the Mountain Lime- 

 stone in the vicinity of Bristol. By the Bet: D. Williams, B.G.S. 



The author stated, that having recently discovered remains of mountain-lime fish 

 in a thin conglomerate which mineralogically appeared to belong to the old red 

 sandstone, be was induced to inquire what other evidences existed of a passage 

 between these two formations ; in this respect he found them singularly deficient 

 compared with the neutral beds and common alternations he had been accustomed 

 to meet with in Devon and Cornwall, between any two consecutive divisions, of 

 which a notable instance existed between the floriferous and carbonaceous series and 

 the overlying killas : near Bristol, however, it was all a hard junction ; the mountain 

 limestone and old red sandstone were there in juxta-location, but the links and 

 ties which determine gradation and uninterrupted succession elsewhere, were all 

 wanting. 



The mode adopted by Mr. Williams of ascertaining the genera and species of the 

 fish, as least liable to error, was by first comparing such palates as he possessed, with 

 all the care he could, with the plates of Agassiz, and having identified them satis- 

 factorily, he referred to the text for the formation and locality, which in every case 

 gave mountain limestone in either England or Ireland. This process of determination 

 gave the following genera and species, viz. Cochliodus contortus, Helodus simplex, 

 Psammodus turgidus, P. cinclus, and P. reticulatus. 



On the south bank of the Avon (below the red breccia which contained the Ich- 



