76 MIDDLE ALBIAN STRATIGRAPHY 



at 7 feet 6 inches to 7 feet (2-286 to 2-133 m.) above the base crushed Hoplites (H.) spp., 

 occur with the shell, indicating the spathi Subzone. 



Tilmanstone 



The original manuscript accounts of the succession shown in the Shafts Nos. 1, 2 

 and 3 of the Tilmanstone Colliery are preserved in the Institute of Geological 

 Sciences. The collecting was carried out by Burr and Griffiths. Griffiths, then 

 employed as the Survey fossil collector, knew the stratigraphical value of Inoceramus 

 sulcatus and /. concentricus and it is possible to state with some confidence from the 

 Log that the junction between the Upper and Lower Gault occurs at a depth of 870 

 feet (265-17 m.) in the No. 1 Shaft (TR 288505) and that the Lower Gault is 62 feet 

 4 inches (18-99 m -) thick. From the account of the No. 2 Shaft (TR 288504), how- 

 ever, the Lower Gault appears to be only about 52 feet (15-85 m.) thick. The 

 possible explanation of this difference in thickness is provided by the No. 3 Shaft 

 (TR 288505) which showed the Gault to be affected by faulting. Whether this 

 faulting is a posthumous movement of the Tilmanstone Fault which affects the 

 Palaeozoic rocks and earlier Mesozoic rocks is not clear. Nonetheless, it is readily 

 apparent that the Lower Gault at the Tilmanstone Colliery is very thick. Very little 

 material has been preserved from these shafts but one specimen (GSM. Zm 5153) is of 

 considerable interest. It is an early form of Lyelliceras known to occur in the 

 eodentatus Subzone in France, but unfortunately no depth has been recorded against 

 the specimen. It is interesting to note that in No. 2 shaft at a height of 21 feet 8 inches 

 (6-6o m.) from the basal conglomerate a ' 3 inch band of Ammonites interruptus ' was 

 recorded. This might indicate a considerable expansion of the dentatus Zone sediments 

 in this area. Further evidence of this is provided by the material from the Shaft of 

 the old Guilford Colliery (TR 281469) 2\ miles SSW. of Tilmanstone. 



Guilford Colliery 



The shaft of the Guilford Colliery, situated near the south-western end of Walder- 

 share Park, Coldred (TR 281469) is now disused. Fossils collected from the Gault 

 during the sinking of the shaft are preserved in the Institute of Geological Sciences 

 (presented by the Kent County Education Authority), and in the collection of 

 Brigadier G. Bomford to whom I am particularly indebted for permitting me to 

 examine his material. Unfortunately, the depths indicated for the individual 

 specimens presented by the Kent County Education Authority is suspect. It seems, 

 however, that at about 851 feet (259-38 m.) depth, the lautus Zone nodule bed at the 

 top of the Lower Gault was reached. This contains material of daviesi Subzone age 

 as well as of cristatum Subzone age, and is, therefore, comparable to the nodule bed 

 at the outcrop to the west. If this depth of 851 feet (259-38 m.) is correct then the 

 Lower Gault is 59 feet (17.98 m.) thick, a little thinner than the No. 1 shaft at 

 Tilmanstone. 



The only definite information about the Lower Gault here is provided by Brigadier 

 Bomford's collection made from the tip heap of the shaft. This includes material 

 from a nodule bed of lyelli Subzone age which yielded Lyelliceras lyelli (GB. 5443, 

 5447, 5446), L. radenaci (Pervinquiere) (GB. 5445), Protanisoceras (P.) buvignieri (GB. 



