290 The Naturalist of Cumbrae. 



the precipitation will be seen to go on far more 

 rapidly than in the purely fresh water. 



" From these results, and keeping in view the large 

 quantity of suspended earthy matter annually carried 

 down by rivers, and that a large proportion of it is 

 precipitated as soon as it comes in contact with the 

 water of the sea, we can easily understand how the 

 courses of rivers within the influence of the tide get 

 so branched in many cases by the precipitated mud 

 silting up the course of the river at one place and the 

 obstructed water at floods forcing a new channel at 

 another and from the same cause deltas at the 

 mouths of rivers may in a great measure be formed. 



" Whatever changes may have taken place relatively 

 to land and sea from other causes, it does not appear 

 that deposits from fresh water currents can be carried 

 far seaward. It is true that the colour of the sea may 

 be affected far beyond the embouchure of the river. 

 It has been stated that the discoloration of the sea by 

 the water of the Amazon has been perceptible three 

 hundred miles from the shore. When such a body of 

 water rolls forward in high floods it will keep its 

 course clear for a considerable distance. Besides, the 

 fresh water being lighter than the salt water, much of 

 it may float on the surface for longer or shorter dis- 

 tances according to its volume and speed. Still, even 

 in these exceptional cases we are constrained to believe 

 that the great proportion of the earthy matter must 

 be thrown down long before it reaches that length of 

 travelling. 



"Last night you were suggesting the desirability 

 of trying for microzoa, etc., in the clay immediately 



