118 THE PLIOCENE AND PLEISTOCENE DEPOSITS OF MARYLAND 



nations and to trace them out from point to point. It is not advisable, 

 after having established a sequence in one section, to make a jump of 25, 

 50, or 100 miles to a distant section and conclude that, because a similar 

 sequence of terraces is found in that locality, they must be necessarily the 

 same as were found in the first station. Deformation may have elimi- 

 nated certain terraces and introduced others, and one cannot be certain 

 that the correlation holds until the entire region has been carefully ex- 

 amined with a good topographic map, in order to ascertain whether one 

 set of terraces corresponds to the other. It is, of course, understood that 

 where formations are separated by such slight elevations, an accurate 

 topographic map, published on the scale of a mile to the inch and having 

 contours at intervals of not more than 20 feet, is indispensable. The 

 work cannot be done with any degree of confidence in a region which has 

 not been contoured and accurately mapped. 



Although the surfaces of these various formations are gently sloping 

 plains, yet there are occasionally low elevations which rise above and shal- 

 low, saucer-like depressions which sink below the general level. 



When a plain surface is found abutting against a scarp, or when an 

 elevation rises like an island from the midst of a terrace and is bounded 

 by a scarp on a portion of its circumference, it is interpreted as repre- 

 senting an island against which the waves beat and cut the scarp. An 

 example of an isolated elevation lifting itself above the general level of 

 the surrounding terrace and bounded by a well-defined sea-cliff is seen 

 in Capitol Hill, Washington, where the prominence on which the capitol 

 is located was an island in the Talbot sea. It has a well-developed scarp 

 on the north, west, and east, although toward the south it slopes away 

 more gently. 



On the surface of the Wicomico and Talbot terraces there are a number 

 of minor terraces developed which are separated by low, inconspicuous 

 scarps but a few feet in height. These are located especially toward the 

 heads of the larger estuaries and on the sides of the valleys of the small 

 tributaries. For some time these minor terraces were extremely confus- 

 ing in attempting to establish a method of discrimination between the 

 more important terraces, but it was soon discovered that they were local 



