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Show . 164 U& VM OF INSECTS- SINGtIMB FORMATIONS. of rocks projecting from the mud- plain which surrounds the island. In wading to the shore, w6 struggled through a deep, soft, dark-coloured mass of what at first appeared to be ooae and slimy mud, but which, upon examination, proved to consist almost solely of the larva of insects lying upon the'bottom, producing, when disturbed, a most offensive and nauseous odour. The mass was more than a foot in thickness and extended several yards from the shore. A bejt of soft, bl& ck mud, more than knee- deef), lay b& ween the water and the hard, rocky beach, and seemed to be impregnated with all the villaneous smells which nature's laboratory was capable of producing. ' The point where we had effected our landing was found to- be a protrusion, oft. an isolated pile of inetamorphlc rock above the vast mud- plain, which latter extended to the northward an$ eastward, without a shrub or & bush Qr aT) lade of grass to be seen upon its. surface. This protrusion constated of various kinds of rock, pushed up from beneath, with a dip to the west from nearly perpendicular to 45°. Slate, almost vertical, was found lying side by side with a dark rook filled with pebbles and stones as large as a man's head, consisting of what appeared to me to be granite altered • and burned by intense heat. This dark rock presented some indistinct traces of a laminated structure, and may be slate wry much fused. Large boulders of granite and feldspar or quartz, with scales of mica, lay strewn about, and I observed one with several ' toll- defined cubes of iron pyritee imbedded in it. The slate seemed to be completely filled with pebbles and small broken frag- . - ments of- granite rock, with here and there a cube, of iron pyrites. Boulders of feldspathic rock, seamed with white quartz, and containing thin veins of jasper of a bribk- red colour, are occasionally found in the slate. Near tne western. extremity of the point is a different kind of rock?- the , dir © ction nearly perpendiculars It is of a* more flandy structure, but is filled with the same pebbles. The whole has been in a state of fusion. < The mud- flat, where abovf the level of the water, is thickly covered with round, dark- coloured, circular cakes, precisely resembling, in. form, colour, and appearance, the excrement of cattle dried in the sun. Underneath the dry surface of these cakes is a soft, black, and sometimes greenish mud, which, when. the cake is' moved by the foot, and the dry covering pushed aside, dmits a most fetid, sulphurous odour, poisoning all the surrounding air. The substance . of which these lumps are formed appears to have |
