A SUKVEY OF THE LOWER TEES MARSHES 89 



A Survey of the Lower Tees Afarshcs and of the declaimed 

 Areas adjoining them. 



By J. W. Heslop Harrison, D.Sc. 



I.— INTRODUCTORY. 



The work outlined in the present paper was undertaken for 

 a variety of reasons, but none was more pressing than the 

 obvious need of determining the sahent features of the existing 

 Flora and Fauna of this section of South East Durham before 

 the projected industrialisation of much of the area had 

 exterminated everything. Of great importance, too, was the 

 necessity of comparing the present vegetation with what had 

 been recorded a century ago in such works as Brewster's 

 History of Stockton (1829) and Sharp's History of Hartlepool 

 (1818). 



When first planned, the work was intended to follow 

 ecological lines, both experimentally and otherwise. This 

 plan had to be abandoned immediately owing to the necessary 

 restrictions placed upon photography and map-making when 

 war broke out. Now, I have left the district permanently, 

 and all hopes of continuing my labours in brighter days have 

 vanished. From this it will be seen that, whilst offering many 

 facts of value to the ecologist, my work will prove more 

 interesting to the student who approaches the subject purely 

 from the floristic standpoint. 



II.— GENERAL CONSIDERATION OF THE AREA. 



Topography, etc. 



As a whole, the drainage basin of the river Tees has an 

 extent of some 760 square miles, but of this only the com- 

 paratively small area lying immediately to the north of the 

 river near its mouth, and extending inland to Billingham has 

 been surveyed; this area covers 14^ square miles. 



Geologically, this nook of South East Durham is of Post 

 Glacial origin, and briefly its development took the following 

 course. Soon after the close of the Glacial Period, the Tees 



