Vol. 59.] THE BOULDER-CLAY AT BIGGLESWADE. 377 



Kimmeridge Clay present, we should expect Oslrea deltoidea in 

 numbers, although it is not characteristic of the Upper Kimmeridge 

 Clay. 



Bed No. 4, 6 feet thick, was made up of a stiff, whitish-brown 

 Boulder-Clay, with about 20 per cent, of chalk. Most of this chalk 

 was in the form of a fine powder ; but there were also many pieces of 

 glaciated chalk, some measuring as much as 6 x 4 inches, and flints. 



Bed No. 5, 10 1 feet thick, consisted of a fine silty clay, with chalk 

 in its upper portion. It contained a few flint-boulders, many pieces 

 of glaciated septaria, Oolitic limestone, and sandstone-grit formed 

 of quartzite and glauconite cemented together, very similar to the 

 grit at Bourn (Cambridgeshire), north-east of the well. This portion 

 of the Drift was evidently a sedimentary deposit, probably a glacier- 

 mud. 



Bed No. 6, 7g feet thick. This was the disturbed upper portion 

 of the Gault, and contained many examples of Belemnites minimus 

 and a number of specimens of Inoceramus concentricus. 



Bed No. 7, 7| feet thick, depth 10L§ to 109 feet, is true fossi- 

 liferous Gault- Clay, containing 



Ammonites (Hoplites) interruptus, I Nucula pectinata, Sow. 



Brug. Nuculana like speetonensis, Woods. 



Ammonites (Hoplites) lautus (?) Sow. ; Inoceramus sp. 

 Belemnites minimits, List. \ Cyclocyathus sp. 



Gasteropod. 1 



(The. foregoing fossils were identified by Mr. E. T. Newton, F.E.S.) 



It comprises a bottom junction-bed with many small pebbles and 

 a number of phosphatic nodules, some enclosing pebbles. 



Bed No. 8. At the level of 109 feet the excavation entered the 

 upper water-bearing strata of the Lower Greensand, consisting of a 

 sand made up of quartzite and glauconite-grains, of a sage-green 

 colour, and containing much drift-wood. Concretionary balls of 

 sandstone with concentric layers were also found. The water 

 immediately rose to a height of 58 feet below the surface, and 

 remains at that level. 



Conclusion. 



The conclusion arrived at is, that we have here a trans- 

 ported boulder of Ampthill Clay. The base of this 

 boulder is at 82| feet O.D., and the bottom of the Drift at 

 74 feet O.D. The boulder was probably an outlier, or a portion 

 of an outlier, situated on the Oxford Clay, at a high enough 

 level to be ploughed into by the agent which formed the Glacial 

 Drift, and, becoming dislodged and undercut, was carried along 

 on this ice-foot into its present position, the line of travel 

 being probably from the north-east. The distance from which 

 it was moved may not have been great — perhaps not more than a 

 mile or two — but on this point no definite opinion can be expressed. 

 The septarian layers have a dip of 9°, and relative to the surface- 

 levels of 4°. May this not show that the boulder, in breaking 



