Summary of Geological Observations. 



everywhere rich in tonrmalinc uiul metallic ores, ilmenilp, rhromUe, hematiU and 

 magnetih. In some places garml anil apufiti' are also noticed, while in the 

 schistose surfaces fine filirous aggregates of riianite and xilliiiiiuii/c are common. 



On the Kichuchu Plain, hesides the existence of a lahradorite yncm, the 

 presence is conspicuous of some dikes of bamlt, which ramify and intersect 

 the gneiss-mica-schist formation. This basalt, which constitutes the only 

 evidence of recent volcanic action met by us in the range, is microcrystalline 

 and of holocrystalline type. On the Biamba Plain I further met a diuhusr in 

 which the opaque element is represented by chromite alone. 



Towards 12,000 feet the zone of the mica-schists disappears, and the 

 greenstones come to the surface ; these constitute exelu-sively ,Mts. Baker and 

 Stanley, and are associated with gneiss on the other heights visited by the 

 ex'ijedition. On the western slope of ilt. Baker the identical mica-schists 

 reappear, which we had met in the Molniku Valley, but on the west side they 

 range somewhat higher than on the east. 



The zone of the greenstones is constituted essentially of an amphihiilili- 

 schist, in which the schistose element is more or less evident; it is usually- micro- 

 crystalline and formed of hornhlendf with quartz, and in the second place frhpar 

 (mostly andesite), and in this case it passes over to a diorite schist. From this 

 amphibolic schist are developed some varieties due to the substitution of 

 (K'tinuUtf for hontlilijndt', or else to its association with (jdrnrt, lilofitf and pi/id.reni-. 



Abundant in these rocks are ilincnite and epidole, the latter also forming 

 numerous beds, veins and nodules, some of which are of extraordinary thickness, 

 as much as 30 feet in the longer axis. Moreover, numerous beds of (jmirtzite 

 everywhere accompany the amphiliolic schists, with which in the various 

 mountains are associated other rocks in the following way : — 



Mt. Baker. — Qvartsiferous dimile ; compact amphibolite which forms the 

 Edward Peak, on the summit of which are numerous fulgurites; cri/slaHiiie 

 limestone : chlorite schist, epidosyte, grenatite ; diubase. 



At several points on this mountain are noticed some lenticels, geodes and 

 small veins of pyrites, calco-pyrites and ilmeitile, with jelspars, ijuart: and calcitr ; 

 on Wollaston Peak a small vein of galena with a gangue of calcite crops out. 



Mt. Stanley. — Compact amphibolite ; amphibolic schist with large garnits, 

 diorite and lahradorite diorite which forms the Alexandra Peak, and probably 

 also the Margheiita ; it is noted for its various types of fulgurites, epidodtes and 

 diabase. 



On this mountain also pyrite and especially ilmcnite are plentiful, as are 

 also copper ores : chulco-pyritc tetrahedrites, malachite. 



Mt. LtiGi Di Savoia. — Here also amphibolic schist crops out, although 



389 



