284 The American Geologist. May, 1900 
limestone, these characteristic components being derived from 
the bed rock formations of western Minnesota and Manitoba. 
Gravel cobbles and pebbles from the drift brought in each 
of the confluent parts of the ice-sheet occur together in most of 
the modified drift deposits of Minneapolis; but where they 
closely overlie the red till and are colored nearly like it, the 
pebbles are predominantly of northeastern derivation, with 
little or no limestone. 
SECTIONS SHOWN BY STREET AND RAILWAY GRADING. 
During last year, in my excursions for mapping the Min^ 
neapolis drift formations, numerous sections showing the com- 
plicated relationship of the northeastern and northwestern 
drift were observed where excavations for streets and rail- 
ways have been recently made. Ten of these sections are de- 
lineated on plate VII. One of the two described first is drawn 
as seen on the north side of a street cutting, and the other 
(reversed to correspond with the preceding) is from its view 
on the south side of the same excavation, these two sections 
being parallel and only 30 to 40 feet apart. Nowhere else dur- 
ing my field work, either in New England or in the North- 
west, have I seen so remarkable sections as some of these, or 
found it so dilificult to study out an explanation of the condi- 
tions of the drift transportation and deposition. 
Oil Superior avenue. Very interesting sections were noted 
near the west limit of the city, on Superior avenue, which runs 
from east to west, passing a quarter of a mile north of Cedar 
lake. Sections i and 2 are on this street, almost due north of 
the center of that lake, being close northeast of the smaller 
Brownie lake. These sections, about 500 feet long and 30 feet 
high, shown respectively on the north and south sides of the 
same cutting, consist almost entirely of till. It is yellowish 
gray above in the east part of the sections to a depth of 3 to 
15 feet. An irregularly undulating and partly angular line of 
division, distinct along all its extent of more than 200 feet, sep- 
arates this yellow till, of northwestern origin, from red north- 
eastern till which forms all the section below, having an ob- 
scure lamination, such as is generally observable in the very 
typical till of New England drumlins. The lamination here, 
as there, is curved in parallelism with the upper limit of the 
