347 
descends westward to Youngstown on the Mahoning. Borings at Niles and 
Rome reached level at 70 feet above Lake Erie, showing that the old Grand 
valley grows deeper in the north (65: 149-51). 
They are marked off by the meridians of New Martinsville and Colum- 
bus and include a mass of detail that, in most cases, is very difficult to map 
from the text. The area south of a line between New Martinsville and the 
mouth of Newark river has been studied thoroughly by Tight and mapped 
in detail (Pl. V and 109) and well discussed. The changes here are quite 
profound but they can be read with little difficulty. 
Theh Muskingum has offered much difficulty to its own solution, es- 
pecially within the deeply drift-covered areas. Leverett (65: 158-65) gives 
the most concise summary of the preglacial conditions of the basin, but 
Tight (109, Pl. I) gives a similar general outline, and with local writers 
discusses the region. 
The Blue Rock col is sufficiently plain to separate that part of the 
present stream into north flowing and south flowing portions. The north 
flowing part might have gone north along the present Muskingum or 
northwest up the Licking, but Leverett favors the latter (65: 161). Tight 
is especially responsible for the section drained by the Licking reversed and 
the preglacial Newark (104: 152, Pl. 1; 91: 160) and of Vernon river. 
Much difficulty was experienced in determining the location of the pre- 
glacial channel which carried the drainage of the present Muskingum after 
it reaches the headwaters of the present Rocky river. Todd (117), a local 
writer who has a paper on the preglacial drainage of the Rocky basin and 
an area south, favors an outlet down the preglacial Rocky, but Leverett 
(65: 165) believes that it flowed east into the old Cuyahoga (PI. IV), 
although he admits that the evidence of a slope in the rock floor in that 
direction is meager. He also favors the idea that the upper Tuscarawas 
was continuous with the preglacial Cuyahoga. 
The system of preglacial drainage (Pls. LV, V) collected into Ports- 
mouth river—the lower Scioto revyersed—is fully discussed by Tight, Lev- 
erett and others and is established. Newark, Vernon and Portsmouth 
rivers united somewhere southwest of Columbus, but it is not well known 
just where. After the union of these rivers the direction of their united 
valleys is not yet determined. Leverett (65: 103-4) says on the question: 
‘“Four possible courses were suggested for the discharge from the southern 
end of the Scioto basin: First, southward, down the Scioto from Waverly 
