Allowing now for a large part to be carried off by waters after 

 an elevation, it is evident that there will still remain in some parts 

 among sea-coast formations, indications of their marine origin. 

 Sneh evidence is yet to be found in our upper terraces. And until 

 it is obtained, there is no safety in the inference that the terraces, 





12 Review of Chambers s Ancient Sea Margins, 



1. In many places above the water line, there are beach accu- 

 mulations; and these accumulations are sandy and distinctly 

 stratified. The layers though thin and distinct are irregular, not 

 of very great lateral extent, but frequently blending and chang- 

 ing their direction. There is often a slope in the layers havin 

 the inclination of a beach. 



2. There are drift heaps on many exposed coasts, formed by 

 the winds and higher seas above the true beach accumulations. 

 These also are stratified (or laminated when solidified), each sheet 

 of sand blown over forming a separate layer. The layers are 

 very irregular in dip, often curving (like the top of the drift heap), 

 and frequently changing their direction. They are often cut off 

 abruptly and overlaid unconformably by other layers, as a sand 

 drift is often beheaded by a gale, again to increase by new accu- 

 mulations. Such drift heaps sometimes form interrupted ridges 

 along a coast, forty, fifty or sixty feet in height. 



3. Below the water level, there are often flats or slopes of 

 gravel, sand, or silt. The material is frequently in delicate 

 layers, and the layers may be of wide or small extent, often (when 

 in extended banks) scarcely varying from horizontality yet slop- 

 ing where the bottom slopes. They are frequently rippled by 

 the waves, or agitated into parallel ridges, in some cases even at a 

 depth of five hundred feet, and flexures like those of the rippled 

 surface will be apparent in the layers beneath. Again, when the 

 waves on a shore break and flow over a bank in shallow waters, 

 they roll up the sand in a series of slopes ; such banks may there- 

 fore be composed of horizontal layers, while the layers themselves 

 occasionally consist of subordinate inclined layers. 



4. The sandy beaches in some places contain worn shells; but 

 very frequently they are destitute of such remains, owing to the 

 trituration of the sands destroying those that may be thrown up. 

 The muddy deposits often afford more or less of animal life of vari- 

 ous kinds, and among them shells are common, worn or unworn. 



The muddy deposits containing molluscs and those beach accu- 

 mulations that include worn shells, will together, constitute a cer- 

 tain proportion of a line of coast, and the former a larger propor- 

 tion of the estuaries. The proportion for any coast should be 

 ascertained, that it may be used as a key towards studying the 

 accumulations over the country back. 



5. There is a minimum width for long arms of the sea, which 

 should be compared with the width of interval between opposite ! 

 terraces on rivers. 









