ROCK SPECIMENS FROM THE ISLAND OF SOCOTRA. 
2 77 
nate one with another. A mica-trap is also found. Evidently this is an extension 
of the last group of rocks. A specimen of an epidotic quartzite proves that there 
are, at any rate, some indications of the metamorphic series. 
Following the Motaha river in a south-south-west direction we find pegmatites, 
coarse and fine-grained felsites, red, buff, and grey in colour, together with a green¬ 
stone so much decomposed that it is difficult to decide whether it be augitic or horn- 
i blendic. The specimens prove that the typical rocks of the Haggier range extend at 
least thus far to the east. 
Returning to Ma-aber and continuing the section eastwards for three or four miles 
to Gedidery, Professor Balfour found first more red felsite, and then, near the latter 
place, much variation in the character and the colour of the rocks—“grey, white, 
yellowish, and red beds alternating.” The specimens from these show that the follow¬ 
ing rocks are represented : fine-grained granite, compact felsites, diorite or, possibly, 
hornbiendic schist and decomposed greenstone. It is also seen that the felsite, like 
the granite, is overlain by the usual limestone. 
Between Gedidery and Gharrieh fine-grained granites and compact quartz felsites 
were collected, indicating that the Haggier group is prolonged as far as Khor Gharrieh, 
where these rocks come down to the sea. The granitic series was traced inland up the 
course of a stream, flowing generally north-north-west as far as the hamlet Vishas, and 
is cut by diorites. From this place up the Goahal Valley, in an easterly direction, 
crystalline rocks may be traced beneath the limestone, but some of the specimens 
must, I think, be gneisses, so that the ancient metamorphic secies probably occurs in 
the eastern as well as in the western part of Socotra. Probably it could be traced still 
further east, but Professor Balfour, owing to indisposition, was unable to collect any 
specimens for the next seven miles. The limestone plateau stretches away to the 
eastern extremity of the island, specimens of this rock being brought from Ras Mom, 
a hill at the neck of the long terminal peninsula, which was the turning point of the 
! expedition. 
After retracing his steps for a few miles to the west, Professor Balfour travelled for 
some distance over the limestone plateau as far as Kittim, shortly after leaving which 
place he turned to the north-north-west, passing first over considerable masses of 
rhyolitic breccias, conglomerates, and grits. A specimen was also brought from a vein 
of calcite, containing fragments of red rhyolite and pinkish felspathic granite. Some 
of these fragments appear to be of volcanic origin, and there are masses of compact 
quartz-felsite, and of rhyolite with distinct fluidal structure, which, as Professor 
Balfour remarked, appeared very like lava flows. All these rocks are overlain by 
the plateau limestones. 
From Azorah Professor Balfour turned in a west-south-west direction, following’ 
o 
the Mitgahon gorge down to Baha, a village lying at the base of a peak called Tof, 
the easternmost summit of the Haggier range. Very compact quartz-felsites, and 
rhyolites abound. They form a conspicuous hill called Afero, which appeared to him 
