219 



PLANT ASSOeUTIONS OF FL4MB0R0UGH HEAD. 



T. W. WOODHEAD, Ph.D., F.L.S. 



Advantage was taken of the visit of the Yorkshire Naturahsts' 

 Union to Bridhngton (May 24th to 28th) to make a series of 

 preUminary observations on the plant associations of the 

 Flamborough headland. 



The area generally is so highly cultivated that at first sight it 

 appears to offer little of interest to the botanist ; but closer ex- 

 amination reveals a number of points which are worth recording. 



The area examined was the triangular promontory having 

 Bridlington to Speeton as its base and jutting out six miles to 

 the east into the North Sea. 



The southern edge varies from twenty-five feet at Bridlington 

 to 150 feet at Flamborough Head. From this point its northern 

 border rises to 440 feet at Speeton, and throughout the greater 

 part of its extent consists of precipitous cliffs of chalk, pictur- 

 esquely weathered at the apex into numerous pinnacles and 

 caves and covered by glacial drift of variable thickness. 



Boynton Woods, lying a little to the west of this area, were 

 also visited. The geology of the area has been carefully studied 

 by numerous workers ; the most detailed account being that 

 by Lamplugh, ' On the Drifts of Flamborough Head ' {Quart: 

 Joiirn. Geol. Socy., 1891), and to this I am indebted for the 

 following brief account of the surface deposits. The vegetation 

 of the area is determined mainly by the covering of glacial drift, 

 and only to a slight extent by the underlying chalk. As deter- 

 mined by Lamplugh the glacial deposits consist of three series, 

 viz. : (i) a lower dark boulder clay ; (2) an intermediate series 

 of more or less stratified material ; and (3) an upper brown or 

 red boulder clay, often discontinuous over the crests of the hills 

 and mounds. 



A striking feature of these deposits is an L-shaped chain of 

 Kame-like or Esker-like mounds and ridges which extend from 

 beyond Speeton and pass eastward in line with the coast to 

 Sanwick. Here the chain bends sharply to the south across 

 the headland, passing through Flambro' village, and terminates 

 at Beacon Hill to the east of the South Sea Landing. As 

 Lamplugh points out this chain of mounds marks the terminal 

 limit of the great ice-sheet, and the material of the mounds was 

 laid down during the period when the ice remained nearly 

 stationary. This was followed by a period of fluctuation 

 resulting in the deposition of the intermediate beds. Finally a 

 great advance of the glacier took place, and spread over and 

 even beyond the area occupied by the previous flow. This was 



1912 July T. 



