NATURAL HISTORY SOCIETY OF GLASGOW. 153 



loughs, many of them of considerable size ; the bogs, mountains, 

 woods, marshes, sands, and cultivated ground, all together 

 present a variety of conditions most favourable to the student of 

 natural history. , 



I propose now briefly to describe the general Natural History 

 of the county, giving some account of the Geology, Botany, 

 Zoology, and Archaeology of the districts, but reserving more 

 special references to points of interest for some future occasion. 



Geology. — The distribution of the primary and metamorphic 

 rocks composing the "back-bone" of county Donegal, calls for 

 no special remark. In very local patches and in very small 

 quantities the more valuable minerals and metals occur, but 

 although companies have been formed to develop the so-called 

 mineral wealth, smokeless chimneys and unsightly ruins are all 

 the results which mark the site of conspicuous failure. 



Lead, copper, and silver have been at various times sought for, 

 but though found to exist, they were not in such quantities as 

 would pay. 



Occasional specimens of gold are found in the quartz, and 

 Mr Harte, county surveyor, has obtained numerous garnets from 

 Gweedore district. 



The post-tertiary deposits are everywhere met with, and are often 

 full of interest. The boulder clay is general over the county, but, 

 unlike its equivalent near Glasgow, is usually an agglomeration of 

 sand and hunch-backed pebbles and large stones ; tough, stony clay, 

 like the " till " of the West of Scotland, does not exist, so far as I 

 know. It is largely developed on the northern coast at Bloody 

 Foreland, where it forms the sea-cliff 100 feet in height, the matrix 

 being a drab-coloured clay. Overlying the boulder-clay in many 

 places can be seen a coarse gravel, highly charged with peroxide of 

 iron, and, where this is overlaid by turf, the stratum of gravel in 

 contact with the turf is seen to be white instead of a reddish 

 colour like the rest. This appears to be caused by the 

 deoxidation of the iron by the organic matter of the turf. I 

 may here mention that bog iron ore is to be found wherever the 

 land is most bleak and barren. Hundreds of tons of this bos 

 ore are shipped annually from Donegal, mostly to Liverpool and 

 London, where it is used for the purification of gas instead of 

 lime, than which it is reported to be more effectual in removing 

 ammonia and sulphur. 



