490 



NA TURE 



[jL'Nt: 



1910 



KOREAN GEOLOGY.^ 



BEFORE the year 1883, when treaties were made 

 by which Europeans were admitted to the 

 country, Korea was a terra incognita to geolog^ists. 

 ('aptain Basil Hall had, indeed, made a few observa- 

 tions upon rocks examined by him on the coast dur- 



FlG. I. — Whirlpool of MyOng-yang frrry showing special topography with narrows and indentation 

 which probably cause the eddy produced in the shore current by the reflex motion. 



The work deals mainly with the southern part of 

 the peninsula, and describes three traverses made by 

 the author ; the important discoveries made by Mr. 

 Yab6 of fossil plants and foraminifera have been of 

 j^reat service in determining the geological age of 

 some of the rock-masses. 



Overlyini;;^ a great mass of gneiss, mica-schist, and 

 phyllite rocks, which may be 

 Archaean in age, though Dr. Koto 

 inclines to the view that they are 

 metamorphosed Mesozoic deposits, 

 there are great masses of granitic 

 rocks, including some very interest- 

 ing types. Above these granites are 

 found a series of strata, which are 

 shown by the plants they contain to 

 be of Jurassic age. AVith these de- 

 posits are found evidences of con- 

 temporaneous volcanic action, while 

 quartz-veins. with gold also occur in 

 them. In Japian these Jurassic 

 strata appear to be underlain by 

 Fusulina limestones of Carbonifer- 

 ous age, and anthracite beds con- 

 taining Rhcctic plants. Rocks of 

 this age appear to occur in other 

 parts of the peninsula, but not in 

 the district examined by Dr. Kot6. 



Of younger age than the Jurassic 



appear to be the series of eruptive 



rocks which our author classes as 



'• Neogranites." These consist of 



quartz-porphyry (quartz-tsingtauite) 



and orthociase-porphyry (t s i n g- 



tauite), with a variety of granite- 



porphvrv for which the author proposes the term 



" Masanite "—the name being derived from the port 



of Ma-san-pho— and an aplite-granite (" Grano- 



Dr. Koto regards his masanite as 



ing his voyage in 1818, and casual references may be 

 found in other authors concerning what could be seen 

 from the sea. In 1883 and 1884, however, a German 

 geologist, Dr. Gottsche, made a rapid geological masanite "). 



reconnaissance of the country, and the rock specimens worthv of receiving a distinct name, from the peculiar 

 he obtained were described by Prof. Justus Roth, mode 'of the intergrowth of quartz and plagioclas" 

 Almost simultaneously with Dr. 

 Gottsche, Prof. Gowland, then head 0/ 

 Imperial Mint of Japan, made a 

 journey through the country for the . 

 purpose of archaeological investigation, I 

 and the numerous specimens which he ' 

 collected were described by Mr. (now 

 Sir Thomas) Holland in the Geological 

 Society's Journal for 1891. In the 

 accounts of his explorations in China 

 (1900-3), the late Baron F. von Rich;- 

 hofen was able to give additional par- 

 ticulars concerning the geological 

 structure of the country. Dr. Bundjiro 

 Koto, the author of the work before 

 us, published his account of the 

 orography of the peninsula in 1903, a 

 memoir which has given rise to a con- 

 siderable amount of controversy. 



As the result of the Russo-Japanese 

 war, however, the country has been 

 much more fully opened up, and the 

 Japanese Government has sent out a 

 number of expeditions for the purpose 

 of inquiring into the natural resources 

 of the country. Unfortunately, most 

 of the reports of these explorations are 

 written in Japanese, but Dr. Koto has 

 rendered a great service to geologists by embody- 

 ing the most important results of these recent re- 

 searches in his memoir. 



1 "Journeys through Kor-a." By Prof. B. Koto. From the Journal of 

 the College of Siicnce. T kyo, Japan, vol. xxvi. Pp. 207 + 36 plates. 

 (Tokyo : The University, 1909.) 



NO. 2 12 I, VOL. Sy\ 



Fig. 



—Remarkable erosion-form, viewed from the south. It is a double-paak, formed of ; 

 Mesozoic conglomerate resting upon a gneisS-granite. 



felspar of which it is mainly composed. Thes 

 plutonic rocks pass into a series of effusives class€ 

 by the author as different types of " felsophyres." 



' Lying unconformably upon the greatly disturbe 

 Mesozoic strata, are found sandy strata \vith seams ot 

 poor lignite, while more recent deposits are only 



