66 KEV. E. BABON GEOLOGICAL NOTES [Feb. 1 89 5, 



sides of the much- worn cone consisted of breccia, from which I picked 

 out olivine-basalt, augite-andesite (477, the only specimen I met 

 with in this part of the island), and a fine-grained sandstone, which 

 had doubtless been brought up from the underlying strata. It may 

 here be also mentioned that at the village of Ankatoka, in the 

 Antankarana country, south of Ambohitra mountain, there are some 

 hot springs ; and about 1| mile south of the village of Anivorano, 

 at the south-eastern base of Ambohitra, there is what I take to be 

 a crater-lake, known as Tanavo, about a mile in diameter. 



The mountain-mass lying immediately south-east of Diego Suarez 

 Bay, referred to on the preceding page, is composed chiefly of 

 reddish and greyish limestone (472, 473) which belongs to the 

 Cretaceous series (probably Upper). In some places (as in the town 

 of Ambohimarina) it assumes the aspect of ruined masonry. The 

 strata appear to have a very slight dip northwards. That part of 

 the mass on which the town of Ambohimarina stands (long. 

 49° 26' E., lat. 12° 27' S.) reaches an elevation of 1400 feet above 

 the sea, and about 800 or 1000 feet above the lava-flooded plain to 

 the south and west. No part of the mountain-mass rises much 

 higher than this. In the limestone I found several specimens of 

 a fossil echinoid, which Mr. B. B. Newton identities as Lampadaster 

 Grandidieri. A microscopic section of the rock in which these 

 occur shows it to be ' largely composed of Globigerince.' The rock 

 may therefore be called ' a 67Zo6^mna-limestone.' [B. B. N.] 

 The same section shows other forms of foraminifera, such as 

 Frondicularia, Modosaria, Bulimina (?), etc. 



Evidence of recent elevation of the northern end of the island is 

 to be found in several places. On the low-lying narrow platform 

 adjoining the sea at the base of the mountain -range immediately 

 north of the Biver Lokia, above mentioned, there are distinct patches 

 of coral-bed, as also rock formed of sand and comminuted sea-shells. 

 Again, at a considerable elevation above the sea, on the island of 

 Nosimitsio (long. 48° 35' E., lat. 12° 52' S.), north-west of Mada- 

 gascar, Mr. Parrett gathered shells which, being compared, were 

 found to be perfectly identical with those lying on the sea-shore. 

 The north-west of the island, as far south at least as lat. 14° 20' S. 

 (probably much farther), has also been recently raised, as is proved 

 by the existence of numerous sea-shells lying a few miles inland at 

 a height of, at any rate, 100 or 200 feet. Further, in some of the 

 larger vesicles on the surface of the lava-bed east of the mountain 

 of Ambohitra, some 4 or 5 miles south of the town of Ambohimarina, 

 spoken of above, I found the remnants of a kind of oyster-shell still 

 firmly attached. The distance from the present coast-line where 

 these were found was 8 or 10 miles, and the height above sea-level 

 about 300 or 400 feet. 



All these facts put together seem to point to the following con- 

 clusions in regard to the geology of the northern end of Mada- 

 gascar : — (1) During some portion or portions or the whole of 

 Jurassic and Cretaceous times this part of the island was beneath 

 the sea. (2) It was afterwards raised, and, judging from the 

 apparent absence of fossils later than Cretaceous, was probably above 



