112 



quoted so largely from Mr. Gavet's paper on the Mickleton 

 tunnel and Aston Magna,* wherein lie shows how much the 

 character of the Gravel deposit varies within so limited an area, 

 and which is now recognised as one of the characteristics of ice. 



And now we arrive at that time when the water-shed was 

 considerable, the hills being probably 600 to 700 feet above the 

 sea; and according to Mr. Prestwich, the river action peculiar 

 to each Valley commenced with the High Level Gravels, while 

 the mass of debris, and the large blocks present in the beds, 

 indicate the action of a large volume of water and ice transport. 



The climate began to ameliorate as the Low Level Gravels 

 were approached, and I incline to the belief that most of the 

 terraces occurring in the same, are the result of fresh-water 

 action, re-distributing and depositing the old debris, in the same 

 way as we now see the alluvium formed in our Severn meadows, 

 which, to those who have not studied what is taking place, 

 would appear incredible. f 



And now, probably, a further depression occurred, which 

 brought the sea far into the Valleys, and by tidal action, 

 planed off the surface of the Lias, as there is no agent which 

 vsrill give an uninterrupted level except the sea. I am led to 



* This paper was written many years ago, and before the ice theory was 

 recognised. 



t Mr. John Jones, in his very valuable paper in our Procedings " On the 

 Geology of the Sharpness Point Disti-ict," gives the following letter from Mr. 

 Clegeam, showing the great change in the deposition of sand by the action 

 of the Severn : 



"The sub-contractor of the canal between the Cambridge Arm and Purton, 

 tells me that he retains a distinct recollection of the excavation for the founda- 

 tion of the bridge walls and platform at the Shepherd's Patch, which is now a 

 mile and a quarter distant from the Severn, and that at a depth of from 15 to 

 16 feet below the present surface of the meadows, which are called the ' New 

 Grounds,' they came to the old river mud, upon which were the footmarks of 

 sheep and cattle, as distinct and sharply defined as though they had been 

 made the day before, extending over a considerable area. These marks were 

 filled up with pure, clean sand and mud, sometimes in separate deposits, some- 

 times mingled together. The mud excavated and exposed to the action of the 

 air, dried and divided into laminae about the eighth of an inch in thickness, 

 showing the quiet tidal process." The work referred to was executed thirty- 

 nine years ago. 



