192 MR. T. H. HOLLAND ON ROCK-SPECIMENS FROM KOREA.. 



Shales are frequentlj' found exhibiting traces of incipient altera- 

 tion, with formation of micaceous minerals. 



Quartzites were obtained by Mr. Gowland and by Dr. Gottschein 

 various parts of the peninsula. Dr. H. B. Guppy, during a brief 

 visit of H.M.S. ' Hornet' to the Korean archipelago in 1878, found 

 quartzites and quartz-rock on the island of Mackau. Underneath 

 the quartzite occurred a "highly micaceous rock" and a gneiss 

 traversed by veins of quartz, which also occasionally separated con- 

 tiguous beds. The dip was 15° E.N.E., thus following the general 

 direction of the upper group of crystalline schists *. 



Y. Sedimentary Rocks. 



From the researches of Von Ilichthofen in Northern China, Dr. 

 Gottsche has been able, to some extent, to classify the fossiliferous 

 strata w'hich he met in Korea. In Phyong-an Do and Hwang-hai 

 Do, in the north, occur patches of Cambrian strata ; whilst in the 

 south rocks probably of Carboniferous age are found in Chol-la Do 

 and Kyong-sang Do. Dr. Gottsche has also mapped patches of 

 rocks in the three northern provinces j- w^hich he regards as 

 Tertiary. 



On account of the absence of fossils, Mr. Gowland found it 

 impossible to form any reliable hypothesis as to the age of the 

 stratified rocks which outcropped along the line of route. Some of 

 the sedimentary rocks, however, prove to be of no small petro- 

 logical interest. 



Near Yukei, in the north-east of Chhung-chhong Do, Mr. Gowland 

 observed in a gorge a good exposure of stratified beds of coarse 

 grit and conglomerate, dipping N.N.W. at an angle of about 24:°. 

 A section taken from one of the specimens collected is seen under 

 the microscope to be made up of a variety of rocks, mostly of igneous 

 origin, amongst which various andesites and fragments of granitoid 

 rocks are the most common. Large crystals of quartz with bands 

 of liquid and other inclusions, and flesh-coloured orthoclase, with 

 spindle-shaped, brightly polarizing inclusions, occur either as sepa- 

 rate grains or as micrographic intergrowths. The majority of the 

 andesitic fragments exhibit crystals of enstatite in all stages of 

 decomposition. Some of these have a fine-grained grey matrix ; 

 others a plexus of lath-shaped crystals, with oxides of iron, either 

 remaining as magnetite or converted into haematite and limonite. 

 Chlorite, quartz, and muscovite occur in cracks and cavities as 

 secondary formations. 



Between Haiphyong and Indong, in Kyong-sang Do, there is an 

 extensive development of coarse stratified sandstones, and, in some 



* * Notes on the Geology of the Coreau Archipelago,' Nature, toI. xxiii. 

 (1881) p. 417. 



t Op. cit. pp. 805-870 & pl. viii. 



