Page:Cornwall (Salmon).djvu/24

 CORNWALL with its varieties of crystalline rock, hornblende, and schist, interspersed by later intrusions of serpentine, and volcanic gabbro. But these rocks have been the subject of much controversy, only to be safely entered upon by specialists. Scattered among the granite are intrusions, mainly of porphyries and felspar, known as elvans, and sometimes mistaken for the granite itself. To the S.W. lie traces of submerged forest, and the traditional buried land of Lyonesse; while on the N. coast are more definite rumours of towns and churches de- vastated and buried by drifting sands. These sands are now largely kept under by the growth of reed-grass; they are much valued by farmers as a top-dressing. Of the mining something must be said later. The richest tin and copper district is around Redruth and Camborne, but the lodes extend to Land's End and beyond. Gold has been found in streaming for tin, and silver among lead and copper; iron also, but not of the best quality. Arsenic, once cast away as refuse, has more lately been worked considerably, but the market is now threatened by foreign competition. The hills of Cornwall are many, but are not so high as those of Dartmoor, Wales, or the Lake District. Brown Willy has already been mentioned as the highest; Rough Tor and Kil- marth are about lOO ft. less, and there are at least a dozen that exceed looo ft. Some of the lesser hills equal these in grandeur of appearance and extent of view.