ALLUVIUM. - RECENT FORMATIONS. 769 



^ The composition of peat, according to Sir H. Davy's analysis, consists of from sixty to 

 ninety-nine parts of vegetable matter in the hundred, with a residuum of earths analogous 

 to the subjacent strata, and oxide of iron. Three specimens obtained from different parts 

 of the United States, upon analysis, yielded 



Soluble geine "I Dosedcmatter , 26 . 00 4g . 80 34 . 00 



Insoluble do. J \59-60 43'60 60-00 



Sulphate of lime 4 . 48 1 . 8g ' l . 3g 



Phosphate of lime - - 0-72 0-12 0-24 



Silicates - - . - 9-20 5-60 4-40 



100-00 100-00 100-00 



Lichens, moss, reeds, grasses, heaths, and shrubs of several kinds may commonly be 

 traced in peat; but one particular species of moss, the Sphagnum palustre, enters into it most 

 abundantly, the upper portion of which continues to flourish vigorously, while the lower 

 portion decays and forms a soil. This contemporaneous vegetation and decay, proceeding 

 for a series of years under favourable circumstances, rapidly forms a thick and extensive 

 accumulation, embedding the trees that may have been growing in the locality, previously 

 prostrated by the winds through the roots rotting. George, earl of Cromartie, relates a 

 remarkable case of the rapid formation of a peat district, in about half a century, between 

 the years 1651 and 1699, near Loch Broaw, on the west of Ross-shire. In 1651, when 

 nineteen years of age, he noticed the spot as a plain covered with standing wood, the 

 trees being entirely leafless and stripped of their bark, evidently a pine forest in one of 

 its last stages. Some years afterwards, when again in the neighbourhood, he found the 

 plain completely denuded of its trees, and presenting the aspect of a flat green ground 

 spread over with moss. Upon inquiring what had become of the trees, and who had car- 

 ried them away, he was informed that they had been all uprooted by the winds, and lay 

 underneath the green moss ; and before the year 1699, he states that the country people 

 came there to dig turf and peat. It appears that the fallen timber, upon being soaked by 

 the rains, first became coated with several species of fungi. An adhesive matter formed 

 by the decay of these parasites, and washed off, rendered the soil with which it intermixed 

 capable of retaining moisture, while the trunks of the trees prevented the rains from 

 running off, thus giving rise to a marsh a condition of the surface favouring the growth 

 of mosses, which speedily took possession of it, and ultimately produced the peat. 



Vast peat districts occur abundantly in France, the Netherlands, Germany, Russia, the 

 Canadas, Scotland, and Ireland, and are found in insulated situations in Iceland, the 

 Shetlands, and the Falkland Islands. Ireland has such extensive formations, owing to 

 the prevailing humidity and low temperature of the climate. They occupy nearly one- 

 tenth of the surface ; or, excluding some small mountainous and detached patches, the 

 total quantity of bog has been estimated at 2,831,000 acres, of which 1,576,000 acres are 

 flat red bog, capable of being reclaimed, and 1,255,000 are mountain bog, mostly convert- 

 ible into pasture land. A single bog on the Shannon that of Allen extends fifty 

 miles in length, by from two to three in breadth ; while the great peat marsh of Montoire, 

 near the mouth of the Loire, has a circumference of fifty leagues. The beds, in some 

 instances, have been dug into to the depth of twenty feet, and even to twice that thick- 

 ness; but such in general is their spongy nature, that a mass may usually be reduced by 

 compression to about one-fifth of its original thickness. The rate at which a peat bog or 

 moss advances varies so much under different circumstances, that we are precluded from 

 forming any certain estimate of the antiquity of a formation, otherwise than from data 

 supplied by imbedded animal and human relics. The coins of Gordian found in the peat 

 at Groningen, and the Roman axes discovered in the peat of Yorkshire, throw light 



3D 



