8 



the Kentish Rag is extensively quarried. The summit of 

 this hill commands a most beautiful and extensive prospect, 

 embracing at one view the entire series of formations from the 

 Chalk to the Hasting's Sand, This point was well chosen by 

 Mr. Mackeson to give a short Field Lecture on the Denudation 

 of the Weald, which he illustrated by a series of Diagrams. 



Field Lecture hy Mr. Mackeson on the Denudation 

 of the Weald. 



Mr. Mackeson began by observing that it was very 

 difficult to explain himself clearly to those who had not a 

 previous acquaintance with Geology. They must remember, 

 that all the geological series which were extended before them — 

 the Chalk Hills to the right and the Hasting's beds to the left 

 seen in the distance, embracing as they did vast periods in the 

 history of the globe — were all deposited at the bottom of the 

 ocean or in fresh-water estuaries : — that they must get rid of 

 the notion of the stability of the Land and the unstableness of 

 the Ocean : the reverse was the case. The Ocean which was 

 expanded before them had most probably always retained its 

 level ; the land had and was constantly undergoing alterations 

 in its level, at one time being gradually elevated, (as was the 

 case now with the coast of Norway), and at other times sink- 

 ing below the bed of the Ocean. He exhibited a section 

 shewing the relative position of the Geological series, shewing 

 the igneous rocks forming the lowest, then the aqueous rocks 

 or the deposits of seas formed in the basins of these primitive 

 rocks ; these igneous rocks were constantly elevating or de- 

 pressing the deposits upon them, and thus it is seen that the 

 beds of the Ocean on its surface have been constantly changing, 

 and by the volcanic action underneath upheaved above the 

 Ocean in which they had been deposited. Mr. Mackeson next 

 exhibited a Diagram of the Denudation of the Weald, and ex- 

 plained the denuding action of the Ocean on those beds which 

 were raised had caused the gradual wearing away of all the 

 deposits resting upon the Weald. — We must suppose that, 



