■326 MR. J. W, STATHER ON SHELLY CLAY [Sept. I9I2, 



Humber. In parts it is crowded with marine shells, in a semi- 

 fossil state, the larger bivalves showing signs of crushing, though 

 in some cases the cuticle and colouring are also preserved. Some 

 of the bivalves occur with'their valves united, in the attitude of life. 

 Foraminifera are also abundant. 



I submitted the specimens of mollusca to Mr. Clement Reid, 

 F.K.S., for identification, and he kindly sent me the list and notes 

 ^which follow : — 



From the marine clay — 



Flustra. 



Anomia ephippium Linn. 

 Card ill 111 cdidc Linn. 

 Montacuta, sp. 

 Mytil'us or Modiola. 

 Littorina ohtitsata Linn. 



Litiorlna rudis Maton. 



Onoba striata J. Adams ( = Eissoa). 



Faludesiriua stagnali^ Baster 



{ = Hydrohia ulvce). 

 Zippora memhranacca J. Adams 



' These are all very shoal-water species, and probably flourished just below 

 low-water level ; thej point to a subsidence of the Dogger Bank to the extent 

 of 50 or 60 feet.' 



The chief interest of the shells lies in the support which they 

 afford to the evidence of the ' moorlog ' as to the post-GIacial change 

 of level in the North Sea basin. Granting that the overlying peat 

 was accumulated on low flat land, we find in the shelly clay proof 

 that some part of the same area was previously occupied by shallow 

 salt water, until a slight upward movement brought it above sea- 

 level, and allowed the formation of peat. 



Then, at some time after the ' moorlog ' was formed, the whole 

 area was depressed to its present level. The shelly clay is very 

 different in composition from the sandy deposits at present forming 

 on the shallow bed of the North Sea, and indicates the proximity of 

 land and the presence of shallow, almost undisturbed waters. 



In conclusion, I may add that I hope, with the help of my friend 

 of the Trawler Fleet, to secure more of this interesting shelly 

 material. 



Discussion. 



Mr. Clement Reid spoke of the importance of these discoveries, 

 which threw light on the origin of the North Sea. Three, or 

 perhaps four, different late-Tertiary deposits had now been found 

 on the Dogger Bank. In addition to the ' moorlog ' and its under- 

 lying estuarine cla}^, former dredgings seem to show that there 

 was a bed containing large striated erratics, and another bed con- 

 taining various extinct Pleistocene mammals ; but, unfortunately, 

 the latitude and longitude of these earlier finds had not been 

 recorded. 



He thought it possible that the considerable depth at which the 

 * moorlog ' and estuarine deposits had now been found might be due, 

 in part, to subsidence through the compression of a thick mass of 

 underlying soft strata containing much organic matter. The sub- 

 merged peat-bed of the Dogger Eank was fully 30 feet lower than 

 the lowest met with in our valleys. 



