HERTFORDSnillE NATURAL HISTORY SOCIETY. XXV 



Field Meeting, 27th May, 1882. 

 HARrEXDEX AND WHEATHAMPSTEAD. 



On assembling at Harpcndcn at about throe o'clock, the members 

 and their friends, numbering between twenty and thii'ty, first 

 inspected a section of the Upper Chalk in a deep roadside cutting 

 on the ascent of the hill between the Midland and Great Northern 

 railway stations, but no fossils were found and the section did not 

 prove to be of much geological interest. 



A short distance farther on, in the direction of Pickford Mill, the 

 botanists of the party detected the toothwort [Latkrcea sqtiamaria) 

 growing on the roots of some large elm-trees ; and in some damp 

 meadows by the side of the River Lea, Thalictrum Jtavum, Meny- 

 anthes trifoliata, and other marsh-plants were found ; and numerous 

 specimens of Cardamine pratoisis with flowers which appeared to 

 be double, from petaloidy of tlie ovules, attracted much interest. 



Leaving the river at Batford Mill, the road leading to Mackery 

 End was followed, the botanists, conchologists, and entomologists 

 assiduously collecting on the way. A small chalk-pit by the side 

 of the road next attracted the attention of the geologists ; and here 

 Mr. J. Saunders, of Luton, made a few observations on the origin 

 of the valley of the Lea. 



The valley of the Lea was, he said, of comparatively recent 

 formation, having been formed subsequently to the Cretaceous 

 epoch, for it was excavated in the Chalk. On the elevation of the 

 bed of, the Cretaceous sea, a plain of marine denudation w^ould be 

 formed, the undulations or irregularities of the surface of which 

 doubtless gave the initial direction to the principal valleys. 

 Vegetation being at first scanty, the denuding power of the rain 

 would be greater than it is now. The deepest part of the valley 

 would become the bed of the incipient river, which would be 

 constantly removing earthy material, the amount of which would be 

 determined by several causes, such as the size of the river, the incli- 

 nation of its bed, and the intensity of the rainfall. Then during the 

 Glacial period for a time the whole of this part of England was 

 submerged beneath the waters of a sub-arctic ocean, through 

 which floated huge icebergs which when dissolved parted with the 

 boulders and earthy material attached to them, and which are now 

 found in the boulder-drift. The formation of the valley having 

 been going on from a pre-historic period to the present time, it 

 might, Mr. Saunders said, be supposed that in some of the river- 

 gravels flint-implements and other articles of human manufacture 

 would be found, and also fossil remains of animals which co-existed 

 with the primitive races of man. Whether such had been found 

 or not, he could not say, but in the adjoining county of Bedford 

 the gravels of the Ouse valley had yielded many flint-imple- 

 ments and remains of the higher Mammalia. 



On leaving this chalk-pit, the party proceeded to Mackery End, 

 the residence of Mr. Luke Howard, grandson of the celebrated 

 meteorologist of that name, Mr. Howard, on receiving the 



VOL. II. — PAKT v. c 



