ZOOLOGY 29 



(16 m.i), the Ure (8 m.), the Nidd (24 m.), the Wharfe (26 m.) and the 

 Aire (30 m.). These all flow into the Ouse (45 m.). The lower parts of 

 the tributaries and the whole of the Ouse are wide, deep and slow-flowing, 

 and form the drainage system of the long, flat plain which crosses the 

 district from north-west to south-east, and comprises most of our area. 

 The Foss (18 m.) drains the northern part of the plain and joins the Ouse 

 at York. On the north lie the North York Moors, and from these the 

 Rye (16 m.) flows into the Derwent (38 m.), which proceeds southwards 

 to join the Ouse below Selby. Beyond the Derwent Valley we extend to 

 the Wolds, which form our eastern boundary, and in this area the only 

 waterway of any importance is the Pocklington Canal. 



We include, therefore, elevated heathlands to the west and north, 

 country of the ' down ' type to the east, while the central portion and that 

 to the south are flat alluvial lands, of which the major part is cultivated 

 very intensively, leaving but a small fraction in a wild or primitive state. 

 That which is still untouched, however, comprises, as would be expected, 

 several most interesting districts, which will well repay a visit. Of those 

 which are readily accessible from York, Askham Bog is perhaps the most 

 noteworthy. This is a genuine piece of unspoilt fenland, situated three 

 miles from York on the road to Tadcaster, and is probably the sole remain- 

 ing representative of a distinct type of country, once prevalent in the 

 Plain of York. Its surface is virgin peat, which reaches to a depth of 

 8 feet, and rests upon clay. Though dwelling-houses have extended very 

 near to it, especially within recent years, and it is perhaps no longer so 

 rich a hunting-ground as formerly, it is still a very famous place, and the 

 records of its fauna extend back for a period of just over a hundred years. 



Flat, sandy commons are a feature of the plain. They are characterised 

 by hummocky surfaces of coarse grass, heather-covered spaces, and in the 

 wetter parts rushes and cotton-grass, frequent marshy hollows, and woods 

 of pine and birch and sallow. Left as these commons have been in an 

 uncultivated state, they have a rich and varied fauna. The nearest is 

 a stretch which begins with Strensall Common, about five miles to the 

 north-east of York, and extends to the districts known as Sandburn and 

 Stockton Commons. At Sandburn the wooded area is much increased. 

 Of the part actually at Strensall that nearest to York has been occupied 

 by the War Office as a military camp for many years, and rendered useless 

 from the point of view of the naturalist, but the rest is good. 



Skipwith Common is smaller in extent, about nine miles south from 

 York ; the area of ponds and marsh is greater than at Strensall. 



AUerthorpe Common is a region of about a square mile in area, about 

 fourteen miles east of York . It has all the characteristics already described , 

 and, though surrounded by well-cultivated country, is itself untouched, 

 and abounds in many good things. 



Of wooded areas there are the districts around Castle Howard and 

 Kirkham Abbey, fifteen miles to the north-east, and the thickly wooded 

 region of Aldby Park and Buttercrambe, about seven miles east. There 

 is woodland at Stillington, and still further to the north we adjoin the 

 richly wooded district of Byland. 



' The distances indicate the length of the rivers contained by our area. 



