402 Dr. Jack on the Geology and Topography 



ravines^ whose general direction is parallel to the coast, though frequently 

 altered and broken by the irregular working of springs and streams. The 

 hills are principally of the trap formation, and exhibit several varieties of 

 basalt, whinstone, and much of the same gray amygdaloidal trap observed in 

 the neighbourhood of Padang. The most remarkable hill in this quarter is 

 detached from the Barrier range, and is called Gunong Bungko, or by Euro- 

 peans the Sugar-loaf. I had lately an opportunity of ascending it, and found 

 it composed almost entirely of irregular masses of basalt or trap, whose bare 

 surfaces are frequently exposed, rising from amid the luxuriant vegetation of 

 the declivities. It had not previously been explored, the shape of the hill ren- 

 dering the ascent extremely difficult. Its elevation is less than 4000 feet ; 

 yet towards the top the trees became stunted, the rocks were clothed with 

 dense moss, and the vegetation assumed a character decidedly Alpine. In the 

 beds of some of the rivers near Bencoolen, particularly that of Silebar, are 

 found pebbles of jasper and chalcedony, with nodules of indurated clay. Iron 

 ores occur not unfrequently, and in one part of the Bencoolen river a bed of 

 coal is laid bare by the stream. Very fine specimens of siliceous petrified 

 wood have also been found in the hills of the interior. 



It was not till 1818 that a journey was accomplished across the island of 

 Sumatra in any part. In that year, a party proceeded from Bencoolen to 

 Palembang; and the facilities of communication are now found to be such 

 that, did not political obstacles intervene, it would no doubt soon become a 

 frequent channel of intercourse between Bencoolen and the more eastern 

 parts of the Archipelago. 



The Pasummah country, which was first visited by Sir T. S. Raffles in 

 1818, is an extensive plain of remarkable fertility, considerably elevated above 

 the sea, as may be inferred from the temperature, the thermometer being usu- 

 ally as low as 65° at 10 a. m. Prom this plain rises Gunong Dempo, which 

 towers above all the mountains of this part of Sumatra, and is estimated to be 

 no less than 12,000 feet above the level of the sea. It is almost constantly 

 emitting smoke ; and hot springs and other volcanic phaenomena are common 

 in its neighbourhood. It has been ascended since Sir T. S. Raffles's visit; 

 vegetation 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 

 Mannae, and indeed the whole barrier range from Bencoolen to Cawoor, are 

 composed of basalt or trap : from the plain of Pasummah I have specimens of 

 quartz abounding with masses of iron pyrites. 



