GEOLOGICAL FEATURES OF BUTESHIRE. 63 



includes an area of 103,953 acres. The number of rock formations, 

 sedimentary and plutonic, which are found within this limited 

 space is truly remarkable, perhaps unparalleled in any tract of like 

 extent on the surface of the globe ; while the varied phenomena 

 which they present in their mutual contacts and general relations 

 to one another are of the highest import in theoretical geology. 



A line running from the north angle of Brodick Bay almost due 

 west to Iorsa water foot divides the island into two nearly equal 

 portions, strikingly different in their geological structure and in 

 their outward features. The northern half consists of a mass of 

 peaked and rugged granite mountains, intersected by deep wild 

 glens, which diverge from a common centre and open seaward on a 

 narrow belt of low land. This belt forms a terrace marking the 

 ancient sea-level, and is bounded inland by cliffs pierced with caves 

 and otherwise sea-worn. 



The southern half of the island consists of a rolling table-land, 

 bleak and unpicturesque inland, but breaking rapidly down seaward 

 into a coast border of great romantic beauty. The general elevation 

 is from 500 to 800 feet, and the irregular ridges which traverse it, 

 most usually in a direction nearly east and west, rise from 1000 to 

 upwards of 1G00 feet. 



The granite nucleus occupies the central and by far the greater 

 portion of the northern half of the island. The three mountain 

 groups already described, with the glens and valleys penetrating 

 and dividing them, consist entirely of this rock. It is remarkable, 

 however, that at no point does the granite reach the coast. It is 

 everywhere enclosed by a narrow band or framework of clay slate, of 

 the second or dark-coloured variety, which completely encircles the 

 nucleus. On the east side of the granite nucleus, above Corrie, this 

 slate band is extremely narrow. On the western side it is much 

 broader; but the lower micaceous band appears only in patches in 

 the promontories ; west of Catacol it is not seen in any great bodies 

 till we pass into Cantire. 



The encircling band of clay slate is succeeded on the east and 

 south by a band of Old Bed Sandstone, which, like the slate band, is 

 of irregular breadth. It begins to overlie the slate at the Fallen 

 Bocks on the north-east coast, and occupies the shore thence to the 

 inarch of Achab Farm, half-a-mile north of Corrie. Here it retires 

 inland, the Carboniferous formations taking its place on the shore, 

 crosses in a narrow band to the west of Maoldon, and stretches thence 

 continuously westward, around the border of the slate, to the mouth 



