568 



Notices from the Minute Books of the Geological Society. 



lieves the gravel fell, and was even forced laterally under the syenite (see fig. 1 . 

 and 2.). In fig. 2. a small horizontal fissure, A, resembling a vein, and about half 



Fig. 1. 



Fig. 2. 







Gravel (a) occupying vertical and horizontal fissures in syenite. 



an inch wide, extends beneath the apparently unmoved rock. This layer also con- 

 tained some small flint pebbles. The gravel is in parts so firmly cemented by a 

 ferruginous sand, as to be able to support the roof of a small cavern, where the 

 substratum had been washed away. 



These observations were made in the year 1833, and when Mr. Trevelyan re- 

 examined the locality in 1835, he saw no reason to change the opinion he formed 

 during his first visit. 



3. On the Illustration of Geological Phenomena by means of Models. By T. Sopwith, 

 Esq., F.G.S. [The notice which accompanied the models was read.] 



The models which accompanied this communication are designed to illustrate 

 the nature of stratification, valleys of denudation, the succession of coal-seams in 

 the Newcastle coal-field, and the effects produced by faults or dislocations of the 

 strata* ; and the author states that his object in constructing them is to meet the 

 impossibility of representing by ordinary drawings more than one plane without a 

 certain amount of distortion, and to explain the totally different phsenomena which 

 the strata beneath a given area may exhibit from those which are exposed on the 

 surface. In order to accomplish fully the latter intention, several of the models 

 are composed of moveable pieces, and by detaching one or more of tliese the effects 

 of dislocations are made apparent, and the real value of a mineral district so cir- 

 cumstanced rendered perfectly clear. 



The models are twelve in number. 



1 . The first represents a district consisting of horizontal strata, and the upper 



* See Mr. Sopwith's work, entitled "Description of a series of Geological Models;" 12mo, 1841. 



