2 I I 
flov., 1910.] An Open Valley near Harrisburg, 0. 
The southern part of the valley has a considerable stream, 
which in its lower course has cut deeply into the valley floor; 
leaving the old stream level as terraces above the present bed. 
The terraces at their down stream end are twenty-five to fitt) feet 
above the present stream level but run out up stream. . nm ar 
terraces occur along the Big Darby, but m a number of instances 
the topographer in making the map has overlooked them, leai mg 
them either on a level with the till plain; or, as m the case where 
this stream comes out to the Darby on the level with the flood 
plain. 
Contour Interval 2.0 feet. 
When one first enters this through valley he is struck by its 
size in proportion to the size of the present streams m it. Three 
facts lead him to believe that the present streams could not have 
carved the vallev. First, these little streams would have needed 
