ET re ee ete Ts 
Pee See 
Ee ee eg hee 
PROS REAPER a SE Le Rare 
1918.] The Geotectonics oj the Tertiary I rrawaddy Basin. 413 
to the south. It appears to be a fairly constant horizon. 
Near Saw, a limestone associated with it contains Ortho rag- 
mina and small nummulites. Similar fossils were also found 
by H. S. Bion near Laungshe. In the rocks below this horizon 
I have found Cretaceous fossils (Hxogyra, Nerinaea, Orbitoi ; 
there is therefore strong evidence that the conglomerates are 
basal eocene. 
From the presence of this belt of conglomerate, I argue 
the presence of a coast-line in lower eocene times near the 
present foot of the Yoma. 
It is very interesting to recall that another conglomerate 
at @ horizon which is doubtful, but certainly later than the 
upper Cretaceous outbursts of serpentine, and most probably 
older tertiary, was found by E. H. Pascoe in the Na ills, 
Assam.” We are led to conclude that there was a land barrier 
In lower eocene times on the site of the present Arrakan Yoma. 
We are probably justified in assuming that in the lower eocene, 
the Irrawaddy basin was under the sea. The Shan plateau 
y 
of Bengal and the Pegu Gulf was in lower eocene times a fairly 
new one, The uppermost Cretaceous was marked in this area 
by considerable volcanic activity. The beds below the basal 
of serpentine along this horizon. This serpentine occurs 
4s rolled pebbles in the conglomerate of the Naga Hills. 
Marine fossils occur in the Cretaceous of the Yoma ; not 
only those mentioned above, but also Cardita beaumonti from 
the foothills of the Yoma in Thayetmyo, while Mortoniceras 
. : 
must conceive then that the Pegu Gulf, as we can now raped 
It, formed a typical geosynclinal area. It received the 
! Rec. Geol Sur. I 
» Geol. Sur. Ind., Vol. XLV, p. 270. Vol. 
XU ene Traverse across the N: aga Hills: Ree. Geol. Sur. Ind., Vo 
em. Geol. Sur. Ind.. V. 1. XL, p. 23 - s 
fot: em. Geol. Sur. Ind., Vol. a 4 311, and Vol, XXI, p. 48, foot 
. 
® Rec. Geol, Sur. Ind., Vol. XXIV, p. 98. 
