XXXIV PROCEEDINGS OF THE 



Aldenham Lodge was reached, and here Mr. C. T. Part joined the 

 members and pointed out the most interesting objects in his garden 

 and greenhouses, and the extensive gravel-pits in his grounds. 

 The adjoining park, jS^e wherries, was then entered, and beyond the 

 house, in the centre of a fiekl, a small opening not easily found, 

 exposed to view the section of the Hertfordshire conglomerate 

 befoi^e referred to. 



After a careful examination of the section had been made by the 

 members, and a few pieces of the rock had been collected, the 

 writer of this report gave a brief account of the geology of the 

 neighbourhood, chiefly as leading to a knowledge of the position 

 of the conglomerate as a member of the Woolwich and Reading 

 Series, and the relation this series bears to the older Chalk and 

 newer gravels which had just been seen. Noticing then more 

 fully the chief points of interest with regard to the conglomerate 

 itself, he said that it was composed of flint-pebbles originally de- 

 rived from the flint-beds in the Upper Chalk and rounded by attri- 

 tion probably on some sea-shore, for the Woolwich and Reading 

 beds in this neighbourhood were rather of marine than of fluviatile 

 or estuaiine origin, and wherever a pebble-bed was found dry land 

 must have existed at no great distance, the heavier matter or larger 

 pebbles remaining near the land, and the softer or more finely 

 divided material being carried out farther from the shore. The 

 presence of the pebble-bed was not exceptional, for it occurred 

 elsewhere in the same position in the Reading beds, as near Watford 

 for instance, but its consolidation into a conglomerate was so, for 

 probably it only occiirred in this position here and at one or two 

 other places in the immediate neighbourhood, as at Radlett Church, 

 near to which it had recently been found in digging the foundations 

 for new school-rooms. It was iilso noteworthy that the cementing 

 agent w<is not as in many other cases of a calcareous nature, for 

 the pebble-bed was consolidated by silica, which, it might be re- 

 marked, had been detected in a gelatinous or soluble state in the 

 mottled clays which form the next higher beds.'* Here and thei-e 

 the surface of the conglomerate was smooth and rounded, apparently 

 showing that it had been subjected to the action of ice, and the 

 way in which it was split up into blocks bore evidence of past 

 upheavals. The hardness and durability of the siliceous cement was 

 evident from the splitting of the pebbles in the general lines of 

 fracture, and sometimes even the pebbles had become softened by 

 a portion of their silica being dissolved out, so that they might be 

 cut with a knife, while the matrix preserved its hardness. 



Returning to Newberries, the members, numbering about forty, 

 were received by Mr. Bagnall, who kindly provided tea and other 

 refreshments, after partaking of which some went by train from 

 Radlett to St. Albans, and others walked back to Bricket Wood 

 Station by The Wylde, slightly varying the route taken in coming. 



* Presfrwich, ' Quart. Joum. Geol. Soc.,' vol. x, p. 123. 



