THE FAUNA OF THE SALCOMBE ESTUARY. 155 



2. Wave-Action. — This is only of importance in the lower part of 

 the harbour near the mouth, and in the area between the mouth and 

 the bar. In the latter region it is of course a very powerful factor, 

 and, as will be seen when the fauna of this part is treated, renders 

 it very barren. Inside the harbour itself there is very good shelter, 

 the effect of which upon the fauna is very marked. There is reason 

 to suppose that the eastern shore is less disturbed than the western 

 in this part. 



Nature of the Bottom- Deposits. — The bottom-deposits will be described 

 in detail when the separate parts of the estuary are considered. 

 Making a general statement, we may say that in the Kingsbridge 

 estuary the soil on the banks consists of fine, sticky mud, over by far 

 the greater part of the area exposed at low tide. On certain parts of 

 the shore, which are exposed to the action of specially strong tidal 

 currents, the mud is not able to deposit to such an extent as it does 

 on the ordinary mud-banks, and we then find a harder deposit, con- 

 sisting of gravel, mixed with a considerable quantity of mud, but 

 lying often very close to the bed-rock. At the north end of Salcombe 

 Harbour the mud of the banks becomes mixed with considerable 

 quantities of sand, and has a much firmer consistency, the firmness 

 of its surface being increased by the fact that it is overgrown with 

 zostera, the roots of which help to keep it compact. In the lower 

 parts of Salcombe Harbour the shore consists chiefly of fine sand, 

 excepting at the upper tidal levels where gravel and muddy gravel 

 are found. 



The nature of the deposit in the channel is only known to us from 

 the results obtained by dredging with an ordinary dredge with net 

 bag, no actual samples of the deposit having been taken. In the 

 Kingsbridge estuary the dredge brought up a mass of decaying sea- 

 weeds, with a good many stones, some gravel, and a quantity of black, 

 sticky mud. Around Snape's Point, where the Kingsbridge estuary 

 narrows and joins Salcombe Harbour, the bottom-deposit consists of 

 clean, fine shell-gravel, and this shell-gravel extends into the first 

 bight on the west shore of the Kingsbridge estuary, which is known 

 as "The Bag." 



In the channel in Salcombe Harbour the dredge material consisted 

 of stones and shells, accompanied by very little mud such as was 

 found in the Kingsbridge estuary. In the lower part of the harbour, 

 between Salcombe town and the mouth, a patch of Melobesia ground 

 was found. Outside the mouth of the harbour the deposit is all 

 fine, clean sand. 



