172 NATURAL SCIENCE. Sept.. 



that the Bengal Colliery managers should form a committee to 

 prepare a revised and enlarged map of the Ranigunj coal-field. 

 " The managers would appear to have quite sufficient data before 

 them in the way of borings and shaft sections, which, combined with 

 their local knowledge, should enable them to contribute materially to 

 the production of a lasting standard work of this kind. An initiatory 

 step might be made by supplying managers with copies of the latest 

 revenue and other maps of their districts, on which each gentleman 

 could enter all the data at his disposal according to some settled 

 scheme of geological and mining delineation. The Geological Survey 

 Staff is all too limited for such an undertaking, but by judicious 

 co-operation with a committee of the kind indicated, a great deal 

 might be done to effect the desired end." A concrete instance of 

 the assistance that may be so rendered is already to hand in an 

 excellent map of the Giridh coal-field by Dr. Walter Saise, manager 

 of the East Indian Railway Collieries, which is to be presented 

 to the Survey for publication. It is distinctly cheering to find 

 that the Indian Geological Survey does not snub the work of private 

 observers in the way that some other Government Departments 

 are accused of doing. 



Tertiary Rivers. 



The little island of Eigg in the Inner Hebrides has long had 

 a fascination for the geologist. Readers of Hugh Miller's charming 

 book " The Cruise of the Betsey " will remember his description of 

 the Scuir of Eigg, that large wall of curious pitchstone-porphyry that 

 surmounts the southern end of the island, running across it from E. 

 to W. This wall appears to be the remains of a once far larger mass 

 of lava, which flowed down from some adjacent volcano and filled a 

 river valley. The river deposits of this valley, with remains of a 

 pine, are preserved beneath the Scuir. At the meeting of the British 

 Association, Sir Archibald Geikie drew attention to a little rock 

 called Hysgeir, which lies in the sea some eighteen miles west of 

 Eigg. This rock consists of just the same peculiar porphyry 

 as the Scuir, but lies at a much lower level. It therefore 

 seems to prove a further extension of the river-valley, and a descent 

 of it about 35 feet in a mile. Some other islets north of Hysgeir 

 exhibit records of a still older river. In what must have been the 

 valley of this river there are found a succession of coarse river 

 gravels alternating with bedded basalts. The lowest of these gravels 

 contains remarkably large blocks, some as much as six feet in length. 

 Some of the gravels or conglomerates pass into true volcanic 

 agglomerates ; while in other places there are layers of fine tuff, vol- 

 canic sandstone, or shales with remains of land-plants. 



The sequence of events which these various deposits indicates 

 was described by Sir Archibald as follows. " During the outpouring 



