228 ADDITIONAL GEOLOGICAL NOTES 



resting in hollows on the Chalk. In one case at Newport, a 

 boring for a well for the Grammar School was begun in the 

 Glacial-gravel and sand. Instead, however, of the slight thick- 

 ness expected, "the boring tool, after passing to a depth of 340 

 feet, chiefly through loamy beds, did not succeed in reaching 

 the chalk, and the work was abandoned. The drift, therefore, 

 must here go down to a depth of about 140 feet below the level 

 of the sea, how much deeper we know not." 



But the drift-filled channel which most perfectly resembled 

 that at " Lockwood Reservoir " is the one described by Mr. 

 Whitaker at Littlebury, a little more than a mile north-west of 

 Saffron Walden. There the valley of the Cam is cut in the 

 Chalk, and the Glacial Drift is to all appearance confined to the 

 high ground east and west of the river valley, which ranges 

 north and south. At the bottom of the valley are some River 

 Gravel and Alluvium, the village of Littlebury standing mainly 

 on the gravel, which is west of the stream. In five wells the 

 depth to the Chalk varied from 3 to 6 feet only. In two other 

 wells it was 15 feet from the surface ; while a third well ended 

 in sand at a depth of 22 feet. These wells are scattered through 

 the village. But near the centre of the village, and only a few 

 yards more easterly than the wells mentioned, a boring 218 feet 

 deep did not touch the Chalk, the whole of the material pierced 

 through being Drift. The length of this channel is doubtful, but 

 its direction is evidently that of the river valley, where the 

 surface is occupied by river-deposits, just as in the case of the 

 channel beneath the Lockwood reservoir. 



As regards the nature of this deep channel in the Chalk, 

 Mr. Whitaker reviews the various explanations that suggest 

 themselves. These are, he says, " disturbance, sinking in of the 

 Chalk, and erosion." He dismisses, as extremely unlikely, the 

 idea of a fault, or that the gravel has filled in a hollow caused 

 by the local dissolution of the Chalk by chemical action, though 

 he admits that it may have deepened a hollow formed in some 

 other way, and decides that erosion of some kind must have 

 been the agent. And that the channel must have been cut 

 before the deposition ot the Boulder clay on the higher ground 

 on each side of the river valley, in either Pre-Glacial or early 

 Glacial times. 



It appears to me that in the channel under the " Lockwood 

 Reservoir" we have, in all probability, one of the same kind) 



