140 
tensive deposits of modified drift. (4) A slight re-elevation 
of the land immediately after the disappearance of the ice 
and, probably, during the formation of the modified drift. 
The elevation is proved їп other parts of the Boston Basin by 
the occurrence of clay beds above sea-level, and generally, it is 
believed, by cut terraces on the drumlins and marine deltas of 
sand and gravel. (5) The development of the modern shore, 
including the growth of the beaches and marshes, accompanied 
by a slow movement of subsidence. 
There remains now, in order to complete this paper, simply 
the task of setting forth more fully the tangible and material 
faets upon which the foregoing statements rest, taking up the 
topies, so far as possible, in the chronological order. 
DRUMLINS, GLACIAL STRIAE, AND BOWLDERS. 
The unmodified drift or till of this district, so far as it now 
exists above the sea and is not covered by the modified drift, 
occurs almost wholly in more or less typieal drumlins. The 
positions, outlines, heights, and names of these are indicated on 
the general map, so far as they have been determined. 
Rockland Hill, however, is only an incipient drumlin, and 
might be more properly classed as a lenticular slope of till. 
Telegraph Hill, World's End, Planter's and Pine Hills, Tur- 
key Hill, Bear Hill, and others are examples of composite 
drumlins; what were originally separate accumulations of till 
becoming more or less perfectly united by their continued 
growth. 
As the map shows, the longer diameters of the drumlins 
have without exception a strong easterly trend, varying 
between south-southeast in the southern and east.southeast in 
the northern part of the district, and agreeing closely at all 
points with the glacial striae on the ledges. 
The following observations on the directions of the striae em- 
brace the extreme range and are sufficiently numerous to show 
