190 PHYSIOGEAriiY AND GEOLOGY OF THE COASTAL PLAIN PROVINCE. 



and is the last of the terrace formations which began with the Lafayette, the 

 remnants of which today occupy the highest levels of the Coastal Plain, and 

 which has been followed in turn by the Sunderland, AVicomico, and Talbot. 



Beaches, bars, spits, deltas, flood-plains, and other formations composed 

 of gravel, sand, clay, and peat are being built up on this terrace belt and 

 are constantly changing their form and position with the variations in cur- 

 rents and winds. Along the streams flood-plains are formed that in the 

 varying heights of the water suffer changes more or less marked. On the 

 land the higher slopes are often covered with debris produced by the action 

 of frost and the heavy downpours of rain which form, in certain places, 

 accumulations of large proportions known as talus and alluvial fans. 



A deposit of almost universal distribution in this climate is humus or 

 vegetable mold, which, being mixed with the loosened surface of the under- 

 lying rocks, forms our agricultural soils. The ultimate relationship there- 

 fore of the soils to the underlying geological formations is evident. 



The deposit of wind-blown sands more or less apparent everywhere, as 

 may be readily demonstrated at every period of high winds, is especially 

 marked along the sea coast, particularly in the vicinity of Cape Henry where 

 sand dunes of large dimensions have been formed. The accumulation of 

 vegetable debris in bodies of water lying in undrained regions and in ponded 

 creeks is also considerable in many places. This is well shown in the com- 

 paratively thick deposits^ of partially decayed vegetation in the Dismal 

 Swamp. Other accumulations in water and on the land are going on all 

 the time and with those already described represent the formations of Recent 

 time. 



