ANNUAL ADDRESS, MDCCCLXXIII. 27 



mentary matter more or less comminuted, and which by 

 the simple force of gravitation have settled to the bottom 

 as soon as the stream or current became still and deep 

 enough. 



Such are the great sandstone rocks of England, well 

 represented in the millstone grit series, and in the great 

 triassic beds which cover such large areas in Cheshire and 

 the Midland counties, and known more familiarly by the 

 name of new red sandstone. The process of formation of 

 sedimentary rocks is well described by Professor Ramsay, 

 who writes, "Suppose a river flowing into the sea: it 

 carries sediment in suspension, and a layer will fall over 

 part of the sea-bottom, the coarser and heavier particles 

 near the shore, while the finer and lighter matter will 

 often be carried out by the current and deposited further 

 off. Then another layer of sediment may be deposited 

 on the top, and another, and another, until, in the course 

 of time, a vast accumulation of strata may be formed. 

 In this manner deltas are formed, and wide bays and 

 arms of the sea have been thus filled up. As they fill, 

 the marshes spread further and further, and, by overflows 

 of the river bearing sediment, rise higher and higher, till, 

 as in cases like those of the Ganges and the Nile, king- 

 doms have been formed of mere loose detritus." (Physi- 

 cal Geology and Geography of Great Britain, p. 4.) 



To show how great sedimentary rock masses and areas 

 can be formed by what is carried into the sea by rivers, 

 I will diverge for a minute to quote an interesting pas- 

 sage in Mr. Jukes's Manual of Geology. At page 401 he 

 writes "The total mineral matter carried down by the 

 Ganges into the sea, according to Everest, is 6,368,077,440 

 cubic feet per annum. Lyell calculates that for the trans- 



