oftJie Island of Sumatra^ 8pc. 191 



veo-etation was found almost to cease near the summit, and a 

 large portion of it bore evident marks of a late and violent 

 eruption. The cold was extreme, and the ascent difficult ; but, 

 owing to a mistake of the guides, the party did not reach the 

 present crater. The hills which separate Pasummah from 

 Mannee, and indeed the whole barrier range from Benccolen 

 to Cawoor, are composed of basalt or trap : from the plain of 

 Pasummah I have specimens of quartz abounding with masses 

 of iron pyrites. 



In the interior of the Lampong country is a lake, the posi- 

 tion of which was not sufficiently determined to enable Mr. 

 Marsden to lay it down in his map. This lake has been twice 

 visited within the two last years by the orders of Sir T. S. Raf- 

 fles : from its neighbourhood are obtained jasper, slate rock, 

 and trap ; there is a hot spring on one side of it. It gives 

 origin, near its southern extremity, to a river which, after 

 passing through the country of Haji, takes the name of Kam- 

 ring, and falls into the Palembang river a little below the 

 town. 



Tulang Bawang rises in Gunong Ompo, to the southward 

 of lake Ranau, and has no communication, as was formerly 

 supposed, with the Palembang. 



Amono- the islands which skirt the western coast of Suma- 

 tra the largest and most important is that of Pulo Nias, which 

 has hitherto remained almost unknown to Europeans. It is 

 alxiut seventy miles long by twenty-five broad, and is for the 

 most part hilly, though none of its mountains are of great ele- 

 vation. It is very populous, and its soil, which is naturally 

 rich, is highly cultivated. The most singular circumstance in 

 its geological structure is the extensive occurrence of calca- 

 reous masses of coral origin, which are found near the surface 

 on almost all the hills, lying immediately above the rocky 

 strata, and to all appearance precisely in their original posi- 

 tion *. These coral masses are in general so little altered that 

 their diffijrent species can be determined with certainty, and 

 even the fragile stems of the Madrepora muricata, and other 

 branched ki7»ds, may be found no otherwise injured than by 

 the pressure of the superincumbent soil, and the constant in- 

 filtration 



• The specimens of cor-.il svliich were received from Pulo Niaf, and wliich 

 were collected from the hills by Dr. Jack, as appears from the labels at- 

 tached to them, are all rounded masses, evidently water-worn ; and they 

 may be divided into two classes. The 1st appears indeed exactly to resemble 

 recent coral ; the structure of the coral is unaltered, and the cells of the 

 polypes empty, and consccpientlv the rock is of the usual lightness of coral. 

 The 'id class consists of a calcareous rock of the ordinary specific gravity 

 of limestone: in specimens Nos. li),]Or>, and liJ.lOG the rock rt-semblts 



some 



