930 J. Parkinson—Foliated and non-Foliated Rocks, 
that part of the series represented by the other. In some localities 
no hard and fast line can be drawn between a series of specimens 
which, taken individually, exhibit many differences, and which have 
been collected over a distance to be measured only by a few yards. 
Distinctly later, though the difference in age need not, geologically, 
be very great, are the granites of the Iyangita, of Itara, and numerous 
other localities, where now and again we may see these rocks clearly 
intrusive into the Gneissose Series. To work back a stage in the 
geological sequence we must appeal to the schists of the Calabar 
River at the Ekankpa Ford, south-east of Isbofia, of the Kwa River 
at Abuton, and of the Akpa Iyefe.’ In each locality (and the three 
given could be supplemented by others from the eastern and north- 
eastern parts of the hills) is a well-marked group of mica- and 
hornblende-schists, associated with granulites, and riddled by acid 
intrusions. In the first and second a banded gneiss is produced by 
a kind of lt-par-lt injection; in the last the dissemination of the 
acid magma was irregular. In regard to the nature of the intrusions, 
the first is now a granitic gneiss; the second a granitic gneiss associated 
with a coarser rock of pegmatoidal habit; in the third, the rock is 
practically a pegmatite. To these petrographical types the remainder 
of the district affords many resemblances, amounting often to identities. . 
Pegmatites crushed and uncrushed are distributed sporadically, but 
far from uncommonly, over the entire area, carrying tourmaline, 
garnet, and muscovite as accessory minerals; here and there, e.g. near 
Netim, Awi, Aking, Awdfong, and Mkpot, mica- and hornblende- 
schists appear, petrographically to be correlated with those of Abuton 
and the Akpa Iyefe. 
The typical mzca-schists of the Akpa Iyefe on the Kamerun frontier 
are rather massive rocks, not conspicuously laminated, and with 
a tendency to become gneissose. On applying a low-power hand- 
lens quartz and felspar become apparent, although crystals of either 
mineral are here and there discernible to the naked eye. In some 
specimens an indication of banding is noticeable. The attempt at 
a gneissose structure in the schists is obvious in many places, and is 
of interest in relation to the very close association they have to the 
intrusive granite. Possibly the structure is due to material which 
permeated from the acid magma, as I have suggested elsewhere * in 
referring to the work of Lacroix and others. 
In two instances clear evidence is obtained of partial liquefaction 
and incorporation of a micaceous schist by a rock of granitic com- 
position. The first of these is from a creek above the Falls of the 
Akpa Iyefe; the second a gneissic band in the very similar mica- 
schists of the river bed above Mkpot. In slides prepared from these 
rocks can be studied the partial solution of felspar, muscovite, and 
biotite by an agent which generally is felspar, but occasionally quartz. 
In the Mkpot example blunt tongues of felspar (apparently albite) 
frequently containing quarts vermiculé have forced their way through 
the edges of the original porphyritic orthoclases of the younger rock. 
1 See outline map of the Oban Hills, Q.J.G.S., vol. Ixiii, p. 314, 1907. 
2 Q.J.G.8., vol. lvi, p. 316, 1900. 
