Revieivs — Geological Survey of Yesso, Japan. 467 



clearly traceable over the ground as the bands of an Agate, the 

 inspection of any large highly contorted cliff section will show how 

 little one can jaresume upon the indications of curvature near the 

 surface for exact knowledge of how the strata are relatively placed 

 with regard to the continuation of these curves in depth, so that it 

 is too much to expect, with Mr. Lyman, that " the contours of any 

 rock bed or vein may be drawn as it is under ground, and its con- 

 tents above or below any given level or within any given limits 

 may be calculated." 



Again, the confusion and unsightliness of so many lines upon a 

 map — the contours of the ground and those of the supposed places of 

 beds below the surface crossing each other at all angles — would create 

 obscurity. Gases may exist in which, the strata not being greatly 

 contorted or faulted, such a map, with lines of different colour for 

 contours of the ground and of the rocks, might be useful to a miner, 

 but for general geological purposes such majDS could never be com- 

 pared with ordinary geological maps and sections. 



The geological part of the Report is interesting but scanty, though 

 the district appears to contain much variety of volcanic, Tertiary, 

 crystalline, and other rocks. It can be readily understood that the 

 full arrangement of notes and observations could hardly be accom- 

 plished for a mere Preliminary Report, but something more might 

 have been expected than the classification of the series by their 

 systems of disturbance and the parallelism of certain axes to the 

 trend of certain coasts, the author t)eing from one passage evidently 

 well aware "that the same system of folds might affect rocks of very 

 different age." 



The following list of rock-groups is given, it is presumed in natural 

 descending order : — 



Alluvium, new and old. 



Volcanic pebble rocks-. 



Volcanic rocks. 



Eocks of the Horuraui Earafto system of folds. 



Coal-bearing rocks or rocks of the Horumui Kuril system of folds. 



Rocks of the Horumui Karafto system of folds. 



Rocks of the Toshibets Kuril system of folds. 



In the Alluvium peat is found, and also lignite with distinct woody 

 fibre. 



The Volcanic pebble rocks (conglomerates) are thought to rest 

 conform abiy on the Coal-rocks at high angles. 



The still slightly active volcanos are chiefly along the shores of 

 Volcano Bay and the adjacent coast. Six of them are. mentioned, 

 the only recent ejections besides vapours being pumice ; and one of 

 the last eruptions (a small one) having taken place on the 1st of 

 March, 1867. Many more of the volcanos of the island have long 

 been quite extinct. 



The axes of the Toshibets group strike nearly north and south. 

 At the gold-fields of the same name the rocks in some localities con- 

 tain great numbers of the "tubes of tube- worms " {Dentalium'>) and 

 " modern looking shells." The rocks ax-e soft and of recent aspect, 



