SILTING UP OF THE CREEKS OF FALMOUTH HAVEN. 15 



700 cubic feet per minute. Here the accumulation of silt lias 

 proceeded at a more rapid rate, the mud being from 6 to above 

 12 feet in depth in its deepest parts. The deep water in Truro 

 Creek has receded greatly in the past three hundred years. In 

 1587 there was but little mud below Oalenick creek, a wide fair 

 channel occupying more than half the river, whilst opposite 

 Malpas Point the bed of the creek has silted up 6 feet since 1681. 



Coming now to more recent surveys — on comparing a plan 

 ,of the river made in 1814, showing the depths of water then 

 existing with one made in 1858, a great increase in the mud 

 banks is seen to have taken place. 



Three inches of mud have gathered between these dates on 

 the bank between Gai'ras Wharf and the Town Quay ; and at 

 Lower Newham the silt deposited is in some cases as much as 

 1 8 inches in depth, and averages 6 inches over the whole width 

 of the river, whilst below Calenick creek at Trevaster Point, a 

 very large accretion has taken place, the average accumulation of 

 mud being 1 foot 9 inches in depth, and the maximum 2 feet 6 

 inches to 3 feet on some banks. 



In the last 25 years a probably accelerated rate of deposition 

 has no doubt obtained. 



On February 5th, 1881, I obtained a sample of water flowing 

 into the creek from the surface of the streets of Truro, and I 

 found that it contained 1 part in 205 in volume of silt in sus- 

 pension. This was of course only from the urban area, and a 

 limited quantity. The Piver Allen when in flood on the 7th, ' 

 containing 1 part in 1000 in volume of silt in suspension as 

 before stated. 



In Calenick creek, owing to the quantities of mine water 

 allowed to flow into it during the last 10 or 15 years, the naviga- 

 tion has been practically stopped ; pools I can remember three 

 to four feet in depth, are now silted up completely, and barges 

 and lighters can no longer come up to the rope-walk quay, it is 

 probable that this creekshas shoaled nearly two feet during the 

 time mentioned. 



Passing now down the river,there has been a gradual accumu- 

 lation of mud in the various banks, causing a narrowing of 

 the fair-way, and the deeper portions of the river shewn in the 

 older charts have considerably silted up. 



