Africa and its inhabitants . oo K oM H ZiO !zi AECHIPELAGO OF MADEIEA. 45 ejected during successive marine eruptions, and round the periphery furrowedby deep vallej-s, which bear witness to. the great antiquity of the lavas. Thebasalts and trachytes resting on a conglomerate of volcanic debris, called ri)Wsofrom its colour, and traversed in every direction by dykes of injected matter,ha^o been eroded by the rains and torrents to a depth of many hundred feetbelow the original surface. No distinct craters are any longer ^^sible ; the escarp-ments have lost their sharp scoriae; all rugosities and
Africa and its inhabitants . oo K oM H ZiO !zi AECHIPELAGO OF MADEIEA. 45 ejected during successive marine eruptions, and round the periphery furrowedby deep vallej-s, which bear witness to. the great antiquity of the lavas. Thebasalts and trachytes resting on a conglomerate of volcanic debris, called ri)Wsofrom its colour, and traversed in every direction by dykes of injected matter,ha^o been eroded by the rains and torrents to a depth of many hundred feetbelow the original surface. No distinct craters are any longer ^^sible ; the escarp-ments have lost their sharp scoriae; all rugosities and rocky points have beenrounded or covered with vegetable humus. Hence, despite the chasms and theirsteep walls, the whole surface has assumed a soft and charming aspect, even where Fig. 19.—AncniTELAQO OP ^VTinE^i^. Scale 1 :1,500, West of ureenwIcV) 0 to xnFeet. Depths. 300 to 3,300Feet. 3,300 Feet unaupwards. 30 Jliles. the rocks have not been clotlied with the verdure of brushwood or forest are no indications of any surviving volcanic life, and earthquakes are of rareoccurrence. The island is traversed from end to end by a high saddle-back, broadeninghere and there into , and again contracting to a narrow ridge. Jiateralspurs branching from the main range, and separated from each other by profoundgorges, terminate on the coast in abrupt headlands, columnar basalt cliffs, andmany-coloured tufas, whose brown, red, and yellow tints produce a very vivideffect. Cape Giram, one of these headlands, about the middle of the south coast, 46 WEST AFIIICA. falls llttlo short of 2,500 foot above the sea. But the general axis lies muchnearer the north side, where the slope ^ is consequently far more abrupt. Heroalso the general aspect of nature is wilder, the headlands more rugged, the coast-line mor
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