J. W. H. Harrison 215 



mate, far and wide, on dale and hill alike, the moors supported huge 

 birch forests relieved along the streams by alders and giving place to oak 

 and mixed woods nearer sea level. Naturally, its fate being linked up 

 with birch and alder, 0. autumnata would be equally widespread. 



But this dry, warm epoch did not last. A steadily increasing rain- 

 fall stimulated the 0ver greedy Sphagnum bogs, and working down from 

 badly drained moors through slacks and gills the developing peat slowly 

 engulfed the birches, as even a casual glance at the stacks of newly cut 

 peat on the remoter moors will reveal, as well as chance exposures else- 

 where. Finally all birches, except those growing in ravines supporting 

 a briskly moving stream and those on well drained slopes lower down 

 the dales, were exterminated. Much later even the latter woodlands 

 were destroyed in satisfying the demands of the mediaeval (if not earlier) 

 exploiter of the outcrops of ironstone. 



Thus under diverse influences the area under birch was reduced to 

 minute proportions, and on the whole of the northern slopes, including 

 the Eston outlier, almost exterminated, as a glance at those portions of 

 Jeffery's 1772 map of Yorkshire given on Figs. 7 and 8 will show. 

 Neither on Eston Moor nor in Lonsdale is any considerable woodland 

 depicted as existing. And the accuracy of the map cannot be impugned, 

 so correctly are the old established oak-ash woods on the north-east 

 slopes of Eston Moor, Airyholme Wood and Easby Wood indicated; 

 these still flourish just where Jeffery places them. 



Such a fate as befell the birches would inevitably have overtaken the 

 insect had not the close botanical relationship of birch and alder always 

 enabled it to use the latter tree as food. And these facts, fortunately 

 enough, put us in the position of being able to assert that toward the 

 close of the eighteenth century, when the period of afforestation set in, 

 the northern colonies of 0. autumnata were confined to alders lining the 

 various beck sides and those surrounding certain moorland springs and 

 pools, with the possible addition of stray birches. In particular those on 

 the northern outlier known indifferently as Eston or Barnaby Moor were 

 so limited. 



A dozen years or so after the publication of Jeffery's- map the first 

 attempts at moorland reclamation were made in Kildale and Lonsdale 

 and on Kempswithen by Sir Charles Turner. In Kildale much of the land 

 so reclaimed was destined for agricultural purposes, but in Lonsdale the 

 efforts were directed towards the establishment of plantations including 

 both deciduous and coniferous trees, the upper slopes receiving Scotch 

 fir and larch and the lower oak. 



