T. M. READE ON A DELTA IN MINIATURE. 263 
16. A Detra in Mintarore—rwenty-srven Yuars’ Worx. By 
T. Mertrarp Reapz, Esq., C.E., F.G.S. (Read February 6, 
1884.) 
Introductory.—Vhe rate of sedimentary accumulation has in all 
cases that I know of been calculated from the amount of sediment 
held in suspension in river-water and the mean annual discharge 
of the river. 
It is true, history has furnished examples of towns that have 
once been sea-ports becoming inland towns through the extension 
of river-deltas*; but the information has not been sufficient or 
accurate enough to found an estimate of the rate denudation has 
proceeded at in the river-basins in question. 
The Rake-Brook Delta.—In June 1883 Mr. Joseph Parry, C.E., 
who has charge of the Rivington Waterworks supplying Liverpool, 
called my attention to the great amount of deposit that had taken 
place in the Rake reservoir since 1856, the year it was filled. 
On visiting the locality in his company, I found that where the 
two forks of the Rake Brook joined the reservoir, a corner of the 
reservoir was cut off by the public road from Bolton to Withnell, the 
communication being by a culvert, stated to be 8 feet high under 
the road, but then nearly silted up with deposit. The following 
plan will explain my meaning more fully. The whole corner of 
the reservoir on the south side of the road, at A on plan (fig. 1), was 
Fig. 1.—Sketch Plan of Miniature Delta, Rake Reservoir. 
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 * Adria was a sea-port in the time of Augustus; it is now about 20 Italian 
miles inland. Ravenna was also a seaport, and is now about 4 miles from the 
main sea. Lyell’s ‘ Principles, vol. i. p. 425 (10th edition). 
