MINERA LOGICAL DESCRIPTION OF TIIE ISLAND OF BANKA. 7^7 
detached from the mass of Breccias and united to a portion of sand¬ 
stone. 
The separate fragments which were united by the cement 
were all rounded at the edges and shewed distinctly the marks 
of attrition : the large planes, slabs or masses which covered the 
surface above mentioned were very durable, and appeared greatly 
insensible to the usual causes producing a decomposition of the rocks 
on this Island. In a few cases only the cement was loose and och- 
reous. I examined one point at the extremity of the hill which 
consisted of a layer of the detached fragments entering into the com¬ 
position of these Breccias, bedded in pure clay ; many had been sepa¬ 
rated by the occasional action of the sea, and were strewed over the 
plain. 
The space occupied by tlie-e recks extends from Sungie Baru to¬ 
wards Teluk Robiya, but I have not been able at all points to trace its 
conjunction with the other mineral substances of the neighbourhod. 
Near the village Sungie Baru I observed it in continued fixed veins 
of rocks projecting from the surface. One of these veins in par¬ 
ticular attracted my notice; it extended from the declivity of 
the hill towards the ocean, in an inclining position and forming with 
the horizon an angle of about 35 degrees. It consisted of a regu¬ 
lar equal stratum of the substance which forms the uniting medium 
of these Breccias, the fracture was very compact, of a dark brown 
colour, exhibiting very minute specks of silex: the surface was re¬ 
gularly tabular and smooth for a length of more than 12 feet; to 
the inferior portion was united another regular layer less compact, 
of a brick red colour, made up of particles of sand and ochre. 
At the extremity of this alluvial hill, 1 remarked an extensive lay¬ 
er of large rounded fragments of sandstone and of nodules of clay, 
presenting different colours on the fracture. I notice this at pre¬ 
sent as I had previously observed in a section of a hill at Fort Nu¬ 
gent the same substances alternating with beds of the common * of 
the island. 
In the same tract of coast, comprised between the rivers of Sun- 
gie-Baru and Teluk Robiya, in conjunction with the Poudingues 
just described, we meet the commencement of a most extensive de¬ 
posit of Iron-ore. It is my object at present to describe some 
of its forms and modifications, and to point out those substances 
which intersect or alternate with it, following the coast towards the 
* Sic Orig. 
