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It may not be improper to give a general descrip- 

 tion of the geological constitution of Great Britain and 

 Ireland. Granite forms the great ridge of hills ex- 

 tending from Land's End through Dartmoor into De- 

 vonshire. The highest rocky strata in Somersetshire 

 are grauwacke and limestone. The Malvern hills are 

 composed of granite, sienite, and porphyry. The 

 highest mountains in Wales are chlorite schist, or 

 grauwacke. Granite occurs at mount Sorrel in Lei- 

 cestershire. The great range of the mountains in 

 Cumberland and Westmoreland, are porphyry, chlo- 

 rite schist, and grauwacke; but granite is found at their 

 western boundary. Throughout Scotland the most 

 elevated rocks are granite, sienite, and micaceous 

 schistus. No true secondary formations are found in 

 South Britain, west of Dartmoor; and no basalt south 

 of the Severn. The chalk district extends from the 

 western part of Dorsetshire, to the eastern coast of 

 Norfolk. The coal formations abound in the district 

 between Glamorganshire and Derbyshire; and like- 

 wise in the secondary strata of Yorkshire, Durham, 

 Westmoreland, and Northumberland. Serpentine is 

 found only in three places in Great Britain; near Cape 

 Lizard in Cornwall, Portsoy in Aberdeenshire, and in 

 Ayrshire. Black and grey granular marble is found 

 near Padstow in Cornwall; and other coloured primary 

 marbles exist in the neighbourhood of Plymouth, 

 Coloured primary marbles are abundant in Scotland; 

 and white granular marble is found in the Isle of Sky, 

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

 land: the principle coal formations in Scotland are in 



