Geological Society. 325 



limestones of Bermuda, and of the shores of Australia, and other 

 places in low latitudes ; a fact which accords with the supposition that 

 this portion of England was for some time in the condition of a bank, 

 very near the surface, — or of an island of small height above the sea. 



The inferences from the new facts mentioned in this paper, the 

 author remarks, do not invalidate the conclusions of previous ob- 

 servers ; showing only that land must have existed and produced 

 vegetation, above the present site of Portland Island, before the de- 

 position of the upper of the two beds, which contains the trees and 

 Cycadeae. The whole of the freshwater strata seems to have been the 

 deposit of a lake, or an estuary, of freshwater, in which (whatever 

 was the cause of the alternations), the waters must have deserted the 

 strata previously accumulated at their bottom, at two successive 

 periods at least ; in each case during a space of time sufficient for 

 the growth of Cycadeae j and in the latter of the two cases, of trees 

 also, — upon the surface of the land thus exposed. 



In conclusion, the author suggests, that the Isle of Portland should 

 be visited from time to time, and frequently, by geologists $ since 

 all the principal appearances of interest are presented by that part 

 of the strata which it is necessary to remove, in order to obtain the 

 valuable stone i so that new phenomena are continually brought to 

 light, and as rapidly defaced, during the course of the operations at 

 the quarries. 



A paper was afterwards read, entitled " Observations on the Ich- 

 thyolites of Gamrie in Banffshire, and on the accompanying Red Con- 

 glomerates and Sandstones," by Joseph Prestwich, Jun., Esq., F.G.S. 



In the summer of 1826, Mr. J. Christie of Banff, in company with 

 Mr. Dockar of Findon, discovered the thin stratum of clay which 

 contains the Gamrie ichthyolites, previously noticed in the bed of a 

 small brook ; but as those gentlemen did not determine the geolo- 

 gical situation of the stratum, the author, at the suggestion of Mr. 

 Murchison, undertook, in a recent visit to Scotland, to investigate 

 its relative position. 



The formations of which the district consists are, micaceous and 

 argillaceous schists, old red sandstone, a red conglomerate, and lias 

 clay and sand. 



The bed containing the ichthyolites the author found to belong to 

 the upper part of the red conglomerate, and he gives the following 

 section of the deposit : 



Soil : 



1 . Loose conglomerate of angular fragments of argil- 



laceous schist, imbedded in a reddish brown, 

 slightly micaceous sand , . . 35 feet. 



2. Red clay 2 



3. Grey clay, with ichthyolites disposed in nodular 



layers about six or eight inches apart 4 



4. Grey, slightly micaceous shale 12 



5. Red conglomerate of quartz and clay slate .... 5 



6. Coarse, micaceous, deep red sandstone 3 



7. Loose conglomerate 12 



