256 PKOCEEDTXGS OF IHE GEOLOGICAL SOCIETY. [April 10, 



record now, and to add to Dr. Oldham's account some remarks of his 

 own as to the very striking secondary effects of this earthquake. 



Cachar, the site of the earthquake of the 10th January, 1869, is a 

 British Province of Eastern India, about 110 miles in length from 

 north to south, by 60 or 70 miles in width. 



Its boundaries on the north and south are Assam and Tipperah (an 

 independent state), and on the east and west Munnepoor and Silhet 

 respectively. 



It is hill- surrounded, except on the south and west, and consists 

 chiefly of extensive plains, through which many large and small 

 rivers wind and wander through ever changing courses in deep muddy 

 beds, in which they rise from 25 to 35 feet in the rains. 



The chief river is the Barak, which is navigable for great dis- 

 tances, the Juroo and other tributaries being still large rivers ; and 

 all, flowing towards the west, discharge into the great Brahmapootra. 



The plains, partly covered with jungle, but also largely cultivated 

 for coff'ee, sugar, mulberries, and now, the writer believes, also 

 for tea, consist of an enormous depth of loose material (the latest 

 washings of the eastern branches of the Himalayas as these emerged 

 from the sea), and, above this, of the prodigious mass of more or 

 less dried and consolidated silt brought down for ages by the net- 

 work of rivers forming the drainage of the existing land. The 

 deep masses of clayey silt which constitute these plains, present that 

 approach towards a stratified structure which always occurs in such 

 deposits from muddy and slow-moving waters. 



The silty mass, however, is not uniform in material at all depths ; 

 from the surface to a depth of 25 or 30 feet it consists of stiff clays, 

 passing into mere sand-beds over large spaces. Over a widely 

 spread but unknown area, these rest upon a bed, from 3 to 6 feet 

 in depth, of slimy ooze, black, full of vegetable and other organic 

 matter, putrid, water-soaked, very porous, and over large areas almost 

 as mobile as a fluid — in fact, a wide-spread greasy quicksand — 

 formed when the conditions supplying the rivers with silt must have 

 differed considerably from what they are now, and over which, in 

 thinner or thicker annual layers, the denser and now consistent mud 

 of the surface of the plains has been gently spread out. 



Owing to these conditions of the plains and circumstances of fall, 

 the river-courses meander in the most sinuous and capricious chan- 

 nels, which are constantly changing their courses, and frequently 

 inosculate with each other, or block themselves up here and there, 

 and often overflow large areas of the plains in the wet season. 



Such appears to have been the scene of the earthquake of the 

 10th January, 1869, or, rather, that of its meizoseismic area ; for the 

 shock or shocks were felt at Calcutta, and far aAvay into Central 

 Bengal. 



The writer has received no clear information as to the apparent 

 horizontal directions of shock at different points of observation, but 

 gathers the general fact that the impulse was probably delivered from 

 a centre of impulse somewhere beneath the hills to the east and north 

 of Cachar. That point, however, is comparatively of little importance. 



