IN THE ANGLO-PARIS BASIN 139 



Royal Society's Symposium on Continental Drift posed many new questions for the 

 stratigrapher and challenged many long held concepts. The important reviews by 

 Wilson (1965 ; 228-251), and Maack (1969) on the formation of the ocean basins drew 

 particular attention to the role and effect of initial major rift, block and transcurrent 

 faulting in the Jurassic and Cretaceous before the pulling apart of the old continents 

 to the positions of the new within the Tertiary. The evidence of faulting and igneous 

 activity indicate that the pulling apart of the continental masses bordering the 

 present day Atlantic commenced earlier in the southern Atlantic (e.g. Maack 1969). 

 In the northern Atlantic the vulcanism commenced in the Tertiary. 



The major faulting must at times have had a profound effect on the distribution 

 and depth of water, and thus the depositional and erosional conditions, in the 

 continental shelf seas. This would produce characteristics quite distinct from the 

 pressure of the African continent against Europe which in the Tertiary culminated 

 in the Alpine ' storm '. During the Albian there is good evidence of the effect of 

 this faulting, associated with the separation of Africa and South America, in and 

 around Africa (e.g. Furon 1963). Even in southern England faulting occurred 

 during cristatum Subzone times associated with marked erosion of Middle Albian 

 sediments. This is but one symptom of one short period of crustal instability which 

 is apparent in both the sediments and fauna in a number of areas in the World and 

 points to a significant event in the development of the Earth. 



The old idea of a Jurassic and Cretaceous North Atlantis continent now foundered 

 below the N. Atlantic was not so far off the mark. However, this ancient land mass 

 was the continental area which is now Greenland and Canada, long before it was 

 broken up and pulled away from Europe since the Tertiary to the present day. It is 

 apparent that the boundary between the Albian ammonite provinces of the deposi- 

 tional areas that is now Europe, and that of Canada and the Western Cordillera of N. 

 America, occurred in the sea-way represented by the sediments in E. Greenland. 



VI. CONDITIONS OF DEPOSITION IN ENGLAND 



From the stratigraphical account of the Middle Albian sediments given above it is 

 possible to obtain some idea of the conditions which influenced their deposition in 

 England. Before commencing the discussion of these it is essential to consider first 

 two factors which provide a key to the interpretation of the field evidence. 



It is apparent that the early Upper Albian {cristatum and orbignyi Subzones) 

 tectonic movements caused the planing-off of the upper surface of the Middle Albian 

 sediments throughout England. This period of erosion, although not as great as 

 Kitchin & Pringle held (1922a), removed a considerable amount of sediment, 

 including marginal deposits. Within a reasonably narrow limit the resulting surface 

 was probably plane, and for the purpose of this study it is taken so to be. From this 

 datum level, by comparing both the surviving thickness and the lithological sequence 

 from place to place, it is possible to make out the configuration of the surface upon 

 which the Middle Albian sediments were deposited. 



It appears that there were only comparatively minor regional tectonic movements 

 within Middle Albian times. These seem to have consisted of minor shifting of the 

 axes of older folds indicated below, causing condensation or increased sedimentation. 



