70 rOEESTS, WOODS, AND TREES 



NOTES 



1. See evidence of Mr. P. E. Martineau before the Royal Commission 

 on Coast Erosion and Afforestation, Minutes of Evidence, vol. ii. part ii. 

 pp. 241-243 (1909), and Quarterly Journal of Forestrij, i. 150 (1907), and 

 iii. 26-31 (1909). 



2. In Colliery Guardian, 19th Jan. 1917, p. 125. 



3. See Cardot, Manuel de L'Arhre, p. 80 (1911). 



4. In P. A. Graham, Reclaiming the Waste, pp. 142-147 (1916). 



5. See Trans. Roy. Scot. Arbor. Soc. xxvii. pp. 30-33, figs. 1-6 (1913). 



6. See Trans. Roy. Scot. Arbor. Soc. xxxi. pp. 108-109 (1917). 



7. Mr. Cadell, in Trails. Roy. Scot. Arbor. Soc. xxiii. 164 (1910), gives 

 an account of the different kinds of pit mounds in Scotland. Some mounds 

 are entirely composed of black argillaceous shale, locally known as ' blaes,' 

 which is not unfavourable to tree growth. If, however, iron pyrites is 

 present, as in some mounds, the sulphuric acid produced by its decomposi- 

 tion combines with the alumina of the shale, forming sulphate of alumina 

 or alum, a soluble salt, which is absolutely destructive to vegetation. The 

 refuse produced in working oil shale in the Lothians is enormous in quantity, 

 and usually goes on fire, being ultimately burnt into a red porous mass, 

 which becomes slowly weathered and crumbling down on the surface, makes 

 good enough soil in the course of time for the growth of larch, birch, and 

 Scots pine. Colliery debris containing fire-clay breaks quickly down into 

 ordinary clay, and may support vegetation well ; but if it contains bitu- 

 minous matter, it will not decompose into a soil suitable for trees. Such 

 black loose material, though devoid of pyrites, has lain in some instances 

 for more than a century without accumulating much natural vegetation. It 

 absorbs the sun's rays and becomes hot and dry in summer, so that plants 

 have great difficulty in starting away at first. 



8. See an article on " The Damage done to Trees by the Shale Industry " 

 in Trails. Roy. Scot. Arbor. Soc. xvi. p. 470 (1901). 



