626 



FARMERS' REGISTER, 



[iNo. 11 



and a green colour in a vein denotes the presence 

 of copper. 



It may not be improper to orive a general de- 

 scription of the (jeological ronstitution of Great 

 Britain and Ireland. Granite form? the great 

 ridseof hills extendins: from Land's End throuffh 

 Dartmore into Devonshire, The hio;hest rocky 

 strata in Somerspfshire are prrauwacke and lime- 

 stone. The Malvern hills are composed of granite, 

 sienite, and porphyry. The highest mountains in 

 Wales arechlorile srhist, or grauwacke. Granite 

 occurs at Mount Sorrel, in Leicestershire. The 

 great range of the mountains in Cumberland and 

 Westmoreland are prophvry, chlorite schist, and 

 Srauwacke; but ofranite is found as their western 

 boundary. Throughout Scotland the most eleva- 

 ted rocks are granite, sienite, and micaceous schis- 

 tus. No true secondarv formations are foimd in 

 South Britain, west of Dartmore ; and no basalt 

 south of the Severn. The chalk district extends j 

 from the western part of Dorsetshire to the east- 

 ern coast of Norfolk. The coal formations abound 

 in the district between Glamorganshire and Der- 1 

 byshire: and likewise in the secondarv strata of { 

 Yorkshire, Durham, Westmorland, and Northum- | 

 berland. Serpentine is Connd only in three places j 

 in Great Britain ; near Cape Lizard in Cornwall, j 

 Portsoy in Aberdeenshire, and in Ayrshire. Black j 

 and gray crranular marble is found near Padslow I 

 in Cornwall ; and other colored primary marbles | 

 exist in the neicrhborhood of Plymouth. Colored 1 

 primary marbles are abundant in Scotland ; and 

 white granular mar' le is found in the Isle of Skv, 

 in Assynt, and on the banks of Loch Shin in Suth- 

 erland : the principal coal formations in Scotland 

 are in Dumbartonshire, Ayrshire, Fifeshire, and 

 on the banks of the Brora, in Sutherland. Second- 

 ary limestone and sandstone are found in most of 

 the low countrieg north of the Mendip hills. 



In Ireland there are five great associations of 

 primary moimtains ; the mountains of Morne, in 

 the county of Down ; the mountains of Donefral ; 

 those of Mayo and Gal way ; those of Wicklow; 

 and those of Kerry. The rocks composing the 

 four first of these mountain chains are principally 

 granite, gneiss, sienite, micaceous schist, and por- 

 phyry. The moimtains of Kerry are chiefly con- 

 stituted by granular quartz, and chlorite schist. 

 Colored marble is found near Killarney ; and white 

 marble on the western coast of Donegal. 



Limestone and sandstone are the common se- 

 condary rocks found south of Dublin. In Sligo, 

 Roscommon, and Leitrim, limestone, sandstone, 

 shale, ironstone, and bituminous coal are f()und. 

 The secondary hills in these counties are of con- 

 siderable elevation ; and many of them hav(^ basal- 

 tic summits. The north coast of Ireland is prin- 

 cipally basalt; this rock commonly reposes upon a 

 white limestone, containing layers of flint, and the | 

 sime fossils as chalk ; but it is considerably harder ' 

 than that rock. There are some instances, in 

 this district, in which columnar basalt is found 

 above sandstone and shale, alternating with coal. 

 The stone-coal of Ireland is principally found m 

 Kilkenny, associated with limestone and grau- 

 wacke. 



It is evident from what has been said concerning 

 the production of soils from rocks, that there must 

 be at least as many varieties of soils as there are 

 fspecies of rocks exposed at the surface of the 

 earth ; in fact there are many more. Independent 



of the changes produced by cultivation and the 

 exertions of human labor, the materials of strata 

 have been mixed together and transported I'roni 

 place to place by various great alterations that 

 have taken place in the system of our globe, and 

 by the constant operation of water. 



To attempt to class soils with scientific accuracy 

 would be a vain labor ; the distinctions adopted by 

 farmers are sufficient for the purposes of agricul- 

 ture; particularly if some degree of precision be 

 adopted in the application of terms. The term 

 sandy, for instance, should never be applied to any 

 soil that does not contain at least ^ of sand ; sandy 

 soils that efiervesce Avith acids should be distin- 

 guished by the name of calcareous sandy soil, to 

 distinguish them from those that are siliceous. 

 The term clayey soil should not be applied to any 

 land which contains less than I- of impalpable 

 earthy matter, not considerably efl'ervescing with 

 acids : the word loam should be limited to soils 

 containing at least one-third of impalpable earthy 

 matter, copiously eflfervescing with acids. A soil, 

 to be considered as peaty, ought to contain at 

 least one-half of vegetable matter. 



In cases where the earthy part of a soil evident- 

 ly consists of a decomposed matter of one particu- 

 lar rock, a name derived from the rork may with 

 propriety be applied to it. Thus, if a fine red earth 

 be found immediatply decomposing basalt, it may 

 be denominated basaltic soil. If fragments of 

 quartz and mica be found abundant in the mate- 

 rials of the soil, which is often the case, it may 

 he denominated granitic soil ; and the same prin- 

 ciples may be applied to other like instances. 



In general, the soils, the materials of which are 

 the most various and heterogeneous, are those call- 

 ed alluvial, or which have been formed from the 

 depositions of rivers ; many of them are extreme- 

 ly fertile. I have examined some productive allu- 

 vial soils, which have been very different in their 

 composition. The soil which has been mentioned 

 belbre, as very productive, from the banks of 

 the river Parret in Somersetshire, aflbrded me 

 eight parts of finely divided earthy matter, and 

 one part of siliceous sand ; and an analysis of the 

 finely divided matter gave the following results: — 



360 parts of carbonate of lime, 

 25 — alumina, 

 20 — silica. 

 8 — oxide of iron, 

 19 — vegetable, animal, and saline matter, 



A rich soil from the neighborhood of the Avon, 

 in the valley of Evesham in Worcestershire, af- 

 forded me three-fifths of fine sand, and two-fifths 

 of impalpable matter ; the impalpable matter con- 

 sisted of 



35 Alumina, 



41 Silica. 



14 Carbonate of lime, 



3 Oxide of iron, 



7 Vegetable, animal, and saline matter, 



A specimen of good soil from Tiviotdale, af- 

 forded five-sixths of fine siliceous sand, and one- 

 sixth of impalpable matter; which consisted of 



41 Alumina, 



42 Silica, 



4 Carbonate of lime. 



5 Oxide of iron. 



8 Vegetable, animal, and saline matter. 



A soil yielding excellent pasture from the valley 

 of the Avon, near Salisbury, afforded one-eleventh 



