CHAP, viii.] SUBMERGED FORESTS. 249 



angular detritus," and to be covered by deposits in the 

 following order : 



1. A blue freshwater-mud deposit, resulting probably 



from the depression of the land. 



2. A surface of plant growth (Iris). 



3. A marine silt with Scrobicularia piperata. 



4. Shingle that forms a ridge, which is at the present 



time encroaching on the level water meadows 

 .behind. 



The physical changes in the district implied by this 

 section are considered by Mr. Godwin- Austen to be as 

 follows : The angular detritus in which the trees are 

 rooted was an old surface soil, formed at a time when 

 the climate was more severe than it is at present, and 

 probably while the boulder clays north of the lower 

 valley of the Severn were falling from melting ice- 

 bergs. This was followed by the epoch of the growth 

 of the forest and of the accumulation of vegetable 

 matter. The overlying blue clay (No. 1) marks the time 

 during which the trees were killed ; the surface of marsh- 

 growth (No. 2) covered with iris marks the epoch when 

 the trees fell; the silt (No. 3) indicates a depression 

 below the sea-level ; and, lastly, the silt was elevated, 

 and the shingle (No. 4) thrown up on its surface, to 

 form the barrier at high-water mark. 



Mr. Godwin- Austen's valuable essay recalled to mind 

 a worked flint which I had found in the angular detritus 

 in 1861, and the Eev. H. H. Win wood and myself re- 

 solved to re-examine the forest-bed and the associated 

 deposits. 



On digging through the layer of undisturbed vegetable 

 matter, we met with ample traces of man's handiwork 

 in flint and chert chippings, as well as a well-formed 



