347 

 YORKSHIRE NATURALISTS AT YORK. 



F. A. MASON, F.R.M.S., AND W. H. PBARSALL, D.SC. 



The August Meeting of the Yorkshire Naturalists' Union was held at 

 York in Bank Holiday week-end (July 30th to August ist), when an 

 enjoyable series of excursions was carried out. Headquarters were in 

 York, members using the Museum grounds for this purpose in the evenings, 

 through the kindness of the Council of the Yorkshire Philosophical 

 Society. Dr. W. E. CoUinge was in attendance, and took a personal 

 interest in explaining the contents of the Museum to those members who 

 were able to find time to see the collections. Representatives of most of 

 the sections were kept well occupied in spite of the abnormally dry 

 conditions prevailing at most of the localities visited. In addition, the 

 meeting was favoured with almost perfect weather. 



The proceedings opened with a visit to Tillmire and Heslington 

 Common oil Saturday, July 30th, and the ornithologists quickly found a 

 subject for enquiry in the numerous pellets of grain skins found there. 

 These were concluded to be bird castings, probably ejected by rooks. 

 Mr. H. B. Booth, the President, also picked up the body of a little owl, 

 which had apparently just been shot. Membei'S met after tea in the 

 Museum grounds, and visited the botanical gardens with much interest. 

 Mr. Scott had kindly thrown open the observatory, and had proposed to 

 make use of the telescope after dark, but unfortunately the night was 

 overcast. 



On July 31st Askham Bog was visited. The Bog was unusually dry 

 underfoot, but a couple of heavy showers more than compensated for 

 this deficiency by thoroughly wetting the undergrowth, without detract- 

 ing from the pleasures of a full and interesting day. 



The following day, August Bank Holiday, was spent at Skipwith, 

 half of the members devoting themselves to the common, while the 

 remainder visited the river. The former party found it distinctly hot, 

 and were well content to spend a pleasant hour with the President 

 watching the birds on a small pool. 



The general meeting was held in Skipwith, after a well earned tea, 

 the President being in the chair. Two new members were elected, and 

 after the reports had been discussed, the proceedings closed with the 

 carrying of votes of thanks to the landowners whose estates had been 

 opened to the Unions' visit, and also to the members of the York 

 Naturalists' Society, who had done so much to make the meeting a success. 



Ecology (W. H. Pearsall). — As was pointed out by Mr. Wroot, 

 the superficial geology of the district is represented almost entirely by 

 deposits of glacial origin. In the three areas visited, the most important 

 of these is a layer of clay or clayey loam, probably deposited in temporary 

 lakes held up by ice blocking the drainage channels. At Tillmire, and 

 to a less extent at Skipwith, these clays are overlaid by sands which 

 appear to have been washed into the lakes by torrential streams, the 

 limit of one of the stream deposits being very clearly marked by a bank 

 6 to 10 ft. high at Tillmire. The thickness of these sandy layers appears 

 to control, very largely, the primitive types of vegetation developed at 

 Askham Bog, Skipwith and Tillmire. 



Sand appears to be absent at Askham Bog, and the development of 

 vegetation over an ill-drained clay, with waters moderately rich in lime, 

 has resulted in the production of 'fen' peat, and of plant communities 

 most closely resembling those of the East Anglian fens, and particularly 

 those existing on Woodwalton Fen, Lord Rothschild's nature preserve. 

 It would be of interest to know if this similarity extends to the animal 

 communities. 



On Skipwith Common there is generally a moderate depth of sand 

 (i to 2 ft.) overlying the basal clay. The distance of the surface above 

 the permanent water level and the poverty of the sand in lime have- 



1921 Oct. 1 



