17 



time for their formation. Fourthly, the hypothesis does not 

 account for the different suites of organic remains found in each 

 deposit. Lastly, it does not account for the constant order in 

 the position of alluvial and diluvial debris. Had they been 

 formed in the way which the hypothesis implies, they must 

 sometimes have alternated. Each of these objections might 

 be expanded and illustrated by many details ; but to enter on 

 them would be foreign to my present purpose. 



The details already given in the preceding sections sufficiently 

 explain the origin of common alluvial formations. But there 

 are two classes of phenomena exhibited on several parts of the 

 coast of our island, which are intimately connected with the 

 present inquiries, and do not always admit of easy explanation, 

 viz. 1. Traces of recent marine deposits above the level of high- 

 water. 2. Extensive traces of ancient forests in situations which 

 are constantly overflown at high-water. 



Phenomena of the first class are generally met with on the 

 banks of estuaries where the waters of the sea necessarily undergo 

 great oscillations. By the extraordinary combination of a high 

 spring tide, and a hurricane blowing in the direction of the cur- 

 rent, whales and other marine animals have from time to time 

 been stranded on the banks of estuaries in situations 20 or 30 

 feet above the reach of common floods.* This is not mere 

 hypothesis : we know that by the combination of such circum- 

 stances as these, the sea has two or three times, within the last 

 600 years, risen to an extraordinary elevation on the coast of 

 Holland, and overwhelmed large and populous tracts of that 

 country. 



The existence of submarine forests is not so readily accounted 

 for. Some writers have supposed them to be the effects of 

 earthquakes, which in ancient times have submerged large tracts 

 of forest land bordering on the sea coast. Without pretending 

 to exclude such agents in cases which without them admit of no 

 explanation, I think that in a vast majority of instances it is 

 unnecessary to introduce them. The mean elevation of the sea 

 about every part of our coast is unquestionably constant ; but 

 the actual level of high-water at any given place is dependent on 

 the velocity and direction of the tidal currents, the contour of 

 the coast, and a number of circumstances which are entirely 

 local. In proof of this assertion, it is only necessary to appeal 

 to the fact, that in extensive bays and estuaries, the sides of 

 which gradually diverge towards "the open sea, the tides occa- 

 sionally rise (through the operation of a common hydrostatical 



* Two examples of this kind arc noticed by Dr. Fleming in the last number of the 

 Edinburgh Philosophical Journal, p. 1^4. Such cases must be carefully distinguished 

 from all tertiary deposits; and from such accumulations of marine shells as are seen in 

 the crag-pits on various parts of Norfolk, Suffolk, and Essex. These latter instances 

 unquestionably belong to no natural marine inundation, and are, at least, as old as the 

 diluvium in that part of England. 



