BENSON.— Structural Features of the Margin of Australasia. 107 
Banda Sea) orogenic forces commenced to act, and have affected the region 
Pe 
older Tertiary rocks, have been greatly dislocated ind f olde 
subsequent orogenie epochs. The crystalline schists and gneisses of Borneo, 
western and central Celebes, Buru, Ceram, and north-western New Guinea 
are held by him to be the exposed portions of this ancient platform, and 
he states that they exhibit a enced east-west strike varied to some 
extent by the post-Permian crust-movements.* Wanner an is of the 
opinion, however, that the known instances of an east-west strike in 
the crystalline rocks of Celebes are far too few to establish definitely the 
existence of a pre-Miocene trend-line in this direction, and notes that the 
strike of the Miocene folding and the extension of the plutonic intrusions 
сес therewith (which кы exhibit gneissic marginal facies) is 
ually in a north-westerly to north-north-westerly direction. Thus the 
trend of the Miocene folds in vieni; central, and south-eastern Celebes 
would е to overlap, coulisse-like, the trend of the coeval folds іп Buru. 
north-westerly or north-north-westerly strike is exhibited by the 
тузын» schists, &c., which form the base of the largely volcanic mass 
of the Minahassa Peninsula. In eastern Celebes strikes to the north-east 
have been noted in the slightly folded late Tertiary beds, but the main mass 
of the eastern peninsula consists, according to Wanner (1910), of massive 
horizontally-lying Eocene and Oligocene limestones, marls, and sandstones, 
ocally upturned along a north-westerly strike. Here also Hotz (1913) has 
found grey-blue shales, containing belemnites, which resemble the Jurassic 
rocks of the Sula Islands. Thus the eastern arm of Celebes may per- 
haps form an outlying portion of the more stable region north of the 
zone of intense folds sweeping through Buru, south-eastern and central 
Celebes. It is noteworthy that basic intrusive rocks are particularly 
abundant in the margin of the folded rocks. A vast mass of peridotite 
océurs in south-eastern Celebes associated with diabasic rocks, and these 
extend to the north along the western side of the fault-bounded series 
of depressions extending through Tomori Bay from Tolo to Tomini Gulf 
These ultrabasie rocks were injected apparently-during the late Mesozoic 
orogeny, and the late Cretaceous-Eocene marine sediments rest on their 
eroded surfaces, but ie are, in addition, a series of Middle Tertiary 
intrusions of gabbros 
The trend-lines of s Malay Archipelago are thus traced in accordance 
with son aot s (1922) charting (fig. 2). A point of detail should, however, 
be noted concerning the direction of the individual fold-axes. Brouwer 
(1922) points out that where the general trend of the geanticlinal zone 
is sharply bent, as in Babber, the individual fold-axes cross the main 
tre 
depth and at the surface. The obliquity of the strike-line of the Mesozoic 
rocks of the Tenimber and Kei Islands to the direction assumed for the 
Banda are in that region has had a very different interpretation, as will 
appear below. 
t is conceivable, however, as Professor Brouwer verbally indicated to tho 
nent that the crystalline schists of the region assumed oy Арева to be the pre 
rian basement of the арнат Palaeozoic continent may be really the highly 
: тано representatives of along series of Palaeozoic geosynclinal sediments metamor- 
phosed during the later Palaeozoic orogeny 
