190 



THE COASTAL PLAIN FORMATIONS OF CECIL COUNTY 



to occupy a position lower than wave-base. One therefore, finds pre- 

 served in the clay water-logged trunks and leaves, nuts, etc., and roots 

 of huge trees like the cypress which would tend to sink by their 

 great weight further and further into the soft mud as the trees in- 

 creased in size. The area over which the waves had removed the 

 upper portions of the lagoon deposit can be determined not only by 

 the presence of truncated stumps but also by the character of the 

 contact. Here there is a sharp division between the clay and the 

 overlying sand and gravel while the area over which the beach ad- 

 vanced without cutting would be indicated by a partial mingling of 

 the beach material with lagoon mud. 



A still later stage in the process is illustrated in the' accompanying 

 diagram (Fig. 10) which represents a stage where the waves have so 



Fig. 11. Ideal section showing advance of Talbot shore-line. 



far advanced as to largely destroy the original stream channel. A small 

 portion of the old lagoon still exists at the head of the swamp but its 

 lower portions have long since been submerged and covered over by 

 the advancing beach. The transverse section shows what is left of 

 the lagoon deposits of mud carrying truncated stumps of cypress and 

 other trees which happened to be buried deep enough to escape the 

 destructive powers of the breakers. The broken line indicates the 

 outline of the clay lens. Fig. 11 is a section through the same region 

 made at right angles to the one just described. At D the breakers 

 are forcing forward the beach upon the meadow. Just off from the 

 beach the waves have swept away the sand and are eroding on the 

 lagoon mud which reached out to them under the beach veneer. At 

 C the waves have succeeded in cutting down the lagoon deposit to 

 wave-base and have left behind a thin veneer of sand and gravel as 



