To such an extent is this portion of the area included in southern Iowa, northern Missouri, southern Illinois, and the extreme southern portions of Indiana and Ohio covered with loess, that it has been difficult to determine the relation of its underlying glacial deposits to the more irregular deposits found farther north. At an early period of recent investigations, while making a geological survey of the State of Wisconsin, President T. C. Chamberlin fixed upon the line of moraine hills, which can be seen upon our map, running southward between Green Bay and Lake Michigan, and sweeping around in a curve to the right, passing south of Madison and northward along the line of Wisconsin River, and in another curve to the left, around the southern end of Lake Michigan, as the "terminal moraine of the second Glacial epoch." In Wisconsin the character of this line of moraine hills had been discovered and described by Colonel Charles Whittlesey, in 1866. It was first named the "kettle-moraine," because of the frequent occurrence in it of "kettle-holes." This line of moraine hills has been traced with a great degree of confidence across the entire glaciated area, as shown upon our map, but it is not everywhere equally distinct, and, as will be observed, follows a very irregular course. Beginning in Ohio we find it coinciding nearly with the extreme glacial boundary until it reaches the valley of the Scioto River, on the sixth meridian west from Washington, where it begins to bear northward and continues in that direction for a distance of sixty or seventy miles, and then turns southward again in the valley of the Miami, having formed between these two valleys a sort of medial moraine.[BE] A similar medial moraine had also been noted by President Chamberlin between the valleys of the Grand and Cuyahoga Rivers, in the eastern part of Ohio. Indeed, for the whole distance across Ohio and Indiana, this moraine occurs in a series of loops pointing to the south, corresponding in general to the five gentle valleys which mark the territory, namely, those of the Grand and Mahoning Rivers; the Sandusky and Scioto Rivers; the Great Miami River; the White River; and the Maumee and Wabash Rivers. Everywhere, however, over this area these morainic accumulations approximate pretty closely to the extreme boundary of the glaciated region. [Footnote BE: See map at the beginning of the chapter.] In Illinois President Chamberlin's original determination of the moraine fixed it near the southern end of Lake Michigan, as shown upon our map, but Mr. Frank Leverett has subsequently demonstrated that there is a concentric series of moraines south of this, reaching across the State, (but somewhat obscured by superficial accumulations of loess referred to) and extending nearly to the latitude of St. Louis.