43 
luvion, produced by the action of currents on its own surface or on 
the neighbouring land, we may readily explain the existence of 
these mud grounds in the Irish sea by the motion of the tides; for 
the finer matter will be naturally deposited in those places where 
there is comparatively still water. 
The north and south tides on the east coast of Ireland meet off 
St. John’s point, and the current is slackened for a considerable 
spaee ere it reach that. Hence we have little or no current of tide 
between Lambay and the Isle of Man; and this is precisely the po- 
sition of the great bed of mud. 
In like manner another extent of mud ground occurs in the 
wake, asseamen call it, of the Isle of Man, between that isle and 
the coast of Lancashire and Cumberland; fer the streams, setting 
up St. George’s channel and in by the north channel, meet and re- 
gurgitate on this coast, producing high tides and still water, and a 
consequent deposition in the offing. This mud ground extends from 
off the mouth of the Ribble northward, and to the mid-channel be- 
tweeen St. Bee’s head in Cumberland and the Isle of Man. 
A third but smaller portion lies in Carnarvon Bay, in the wake 
of Brachypult point, where also there is little stream of tide. 
Another in the mouth of Clyde in the wake of Cantire, and 
many smaller in sheltered places. 
As it is evident therefore, that these are alluvial depositions, it 
does not seem too much to admit, that the adjacent portions or zones 
of sand are in all probability the rougher particles of the strata, not 
admitting of being transported so far, or whose finer particles are 
swept off into the still water. 
It would appear, that the current of tide which sweeps these par- 
ticles befote it, so far from carrying them out into the deep water of 
the ocean, tends rather to regorge them against the shores: the 
tidal water, after the reflection from the coast, naturally returning 
