MICHIGAN ACADEMY OF SCIENCE. 
115 
Between the valley of the Puerco river and the base of the Mesa Prieta 
is a flat area inclined downward toward the northeast. At the junction 
of the Puerco river and Poleo creek the surface of this area, here called 
the Mesa Poleo, lias an elevation of approximately 7,500 feet; further 
down the course of the Puerco there is another block with an elevation 
of between 7,000 and 7,300 feet and beyond this to the Cliama the sur- 
face is about 6,500 feet. These three areas are separated by sharp faults 
which are occupied by intermittent streams. It will be noticed that 
the valleys of these streams are very closely parallel to the valleys of 
the Cliama river and Poleo and Capuli creeks. 
The dip of the strata of the Mesa Prieta and the Mesa Poleo are 
slightly to the northeast; on the south side of Poleo Creek the strata 
dip very sharply to the southwest, on the southeast side of the Puerco 
river the strata are nearly horizontal. 
The notes on this quadrangle are here recorded for the use of those 
who wish to study the orientation of the drainage lines in a region where 
the structures is very evident. 
CORRELATION OF LAKE AGASSIZ WITH GLACIAL LAKES IN 
GREAT LAKES BASINS. 
BY FRANK LEVERETT. 
Abstract. 
The moraines which correlate with the Port Huron morainic svstem 
seem to embrace a system that sweeps around the head of Lake Superior, 
from which it appears that no glacial lake could have formed in the 
western end of the Superior basin until after the time of Lake Whittle- 
sey. Lake Duluth probably correlates with Lake Wayne, the successor 
of Lake Whittlesey, each lake being dependent upon a large recession 
from the Port Huron morainic system. The correlative of the Port 
Huron morainic system in the region covered by ice from the Keewatin 
field seems to be found in the “gray drift” border in Minnesota, for 
glacial drainage from the border of the gray drift in the St. Louis basin 
was controlled to a marked degree by the ice lobe in the Superior basin 
at the time of the development of the morainic system at the head of the 
lake, which as stated above, is likely to be the correlative of the Port 
Huron system. A great recession of this western field on this interpre- 
tation would be necessary before Lake Agassiz could come into 
existence. The beginning of Lake Agassiz may, therefore, have been 
as late as Hie lowering of the waters of the Superior basin to the level 
of Lake Algonquin. Some support for this interpretation is found in 
the deformation of shore lines. Studies in the basins of ihe Great 
Lakes have shown that but little deformation had occurred down to the 
time of Lake Algonquin. But during ihe life of Lake Algonquin great 
deformation occurred. The same is true of beaches of Lake Agassiz, 
there having been a great amount of deformation during its life, and a 
splitting of every beach when traced northward. The correlation of 
moraines and the evidence from deformation seems, therefore, to be in 
harmony in making Lake Agassiz a correlative of Lake Algonquin rather 
than of any earlier lake stage. 
