38 Remarks on the Formation of Alluvial Depositee. 



thus produce nearly level strata (Z^^, intermixed with the inclined 

 stratification. Also the materials deposited by the stream before 

 reaching the point c, will be in strata either horizontal or very 

 gently inclined, cj\ In proportion as the mass c ^ is allowed 

 scope to arrange itself in the complete semiconoidal form, Fig. 

 24, the successive strata will consist of distinct zones, all having 

 reference to the point (5) of the divergence of the stream as their 

 centre. In the language of Werner, they will have the arrange- 

 ment of mantle-shaped formations. Where the field of action is 

 limited by the convergence or parallelism of the sides (Fig. 26), 

 as at the head of lakes or in deep estuaries, the inclined strata 

 may be supposed to be nearly parallel planes, inclined at an 

 angle of about 45°. The submerged taluses, traced along the 

 margins of lakes, seas, and of the ocean, may be presumed to be 

 stratified in a similar way. 



When we see a level plain between mountains, we are natu- 

 rally I'eminded of the surface of a lake, and the inference has 

 often been drawn, that such a level has been formed by the sub- 

 sidence of earthy matters to the bottom of the lake. This view, 

 however, will not bear examination. Water flowing at any depth 

 whatsoever is not a lake, but a river ; and it is impossible to ac- 

 count for the distribution of detritus evenly over the bottom, ex- 

 cept by supposing the water to flow at the bottom. Even the 

 fine particles held in suspension are carried but a few miles into 

 the deep water, and can only form a thin film a little in advance 

 of the base of the sub-aqueous cone or talus ; so that, if a deep 

 and extensive lake were drained after hundreds, or even thou- 

 sands of years, its bed would be found in many parts unchanged 

 by the action of its waters, scarce a pebble having advanced be- 

 yond the line which is to be traced along the bottom of all its la- 

 teral terraces and cones. By parity of reason, one of the funda- 

 mental positions of the Huttonian theory, which supposes tliat 

 alluvium is carried into the depths of the ocean and strewn over 

 its bed, cannot be maintained, unless it be proved that there are 

 streams in the depths of the ocean. 



That lakes have in numerous instances been filled up may be 

 readily granted ; but it can only have been by the processes 

 above described. The declivities, represented by the line c dm 

 the diagrams, advancing from every quarter of the lake in pro- 

 portion to the activity of the streams in supplying materials, the 



