326 THE PLANT LIFE OF MARYLAND 



this can retain but little of the downpour. Eivulets form, these 

 combine into larger streams, and soon a channel is begun along the 

 line of the furrow and the work of washing is started. 



Certain types of soil should never have their natural cover of 

 trees entirely removed because of the ease with which the soil par- 

 ticles are washed away in any heavy rain. Such should be perma- 

 nently in forest, and the tree growth so secured would be a source 

 of revenue to the individual owner. The rapid runoff of the rain 

 and snowfall would be checked and the water supply of springs 

 and other sources of stream flow would become more regular. The 

 loose shale soils form agricultural areas of poor returns in the way 

 of cultivated crops, and aside from the possible profits available 

 they are difficult to work. It is such soils as these which should be 

 permanently devoted to the crop of forest trees, and the tree growth 

 on them cared for as if it were a permanent crop, instead of a tem- 

 porary supply which must be used all at once. 



In the more valuable agricultural areas, winter cover crops should 

 be utilized to prevent similar damage by heavy rains upon light loam 

 soils. 



COASTAL ZONE. 



The soils of this region are as a class formed by the deposit of 

 material by water, at a time when the sea level was at a higher 

 point than at present. Under these conditions the various types of 

 sandy and loamy or even clayey soils are found in areas of consid- 

 erable extent and having a nearly level surface. In the portion of 

 the Coastal Plain designated as the "sub-aqueous area" below the 

 present sea level, the same process of deposition of transported soil 

 particles is now going on to form additional areas of nearly flat 

 land. If the whole coastal plain should be raised a hundred feet 

 above its present level, the gentle slopes of the Eastern Shore would 

 extend beyond the present beach line and be correspondingly greater 

 in area. This variation in land area has occurred several times ac- 

 cording to the Geology of the region,* and at each change in level 

 the soil materials have been worked over by the wave and current 



*See Physical Features of Maryland, pp. 144-5. 



