390 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 9, 



If, then, we assume for a moment that these lake-basins were 

 excavated by glaciers, this can only have been effected in one of 

 two ways. 



(1) Either a branch of the Hallstadt glacier turned aside at Ischl 

 up the Aeh valley, forced its way through the narrow at Pfandl, 

 excavated the Wolfganger See, mounted the steep slope on the west 

 to a height of about 500 feet above the present level of the lake, 

 and then, plunging down the slope on the other side of the ridge, cut 

 out the basin of the Fuschelsee. 



(2) Or from the slopes of this ridge and those of the mountains in 

 immediate proximity two glaciers descended, one of which excavated 

 the Fuschel, the other the Wolfganger basin. 



With regard to the first of these hypotheses, it is most difficult to 

 understand how the Hallstadt glacier could split asunder and turn 

 the corner (almost a right angle) at Ischl, or hoAv after this it could 

 be forced up an ascent of not less than 1000 feet in not more than 

 7 miles *, an ascent of about 1 in 35, with nothing in the orography 

 of the neighbourhood to suggest any great additions to the ice- 

 stream. Further, the form of the ridge, sharp, with a well-defined 

 central peak, is wholly unlike what it would have been after the 

 grinding of a great glacier. 



As to the second of these hypotheses, one glance at the dividing 

 ridge is enough to show that it never could have given rise to a 

 large glacier on either side. 



I believe that no third hypothesis is possible. 



We pass on to the lakes on the northern side of the Schaff berg. 

 These three — the Zeller See, Mondsee, and Atter See — are arranged 

 on a (J-like curve, the base of which abuts on the precipices of the 

 Schaffberg range. The firstf, also called the Irr- or Jungfernsee, 

 lies among low hills of Wiener Sandstein, so low that when regarded 

 from the summit of the Schaffberg it appears to open out on the 

 north to the great plain. Its waters descend a well-marked wide 

 valley, which crosses, roughly speaking, the strike of rolling lines of 

 hills of no great elevation, and enters the Mondsee. This lake j 

 now runs up to and curves sharply round to the east beneath the 

 huge precipices forming the northern scarp of the limestone range ; 

 but an arm of it doubtless once extended up the valley by which the 

 water comes from the Fuschelsee. In fact, the lower part of the 

 Mondsee may be said to occupy a prolongation of this valley, which 

 is extended to the head of the Atter See§, — the neck of land dividing 



* If we assume, as I conclude may fairly be done, the deepest part of the late 

 to be opposite to the Falkenstein precipice, it would be in 4 miles. This does 

 not adopt the maximum depth quoted above. 



t About 3 miles long, f broad, 1763 feet above the sea. 118 feet deep. 



+ Rather more than a mile long (?), and about 1J broad, 1563 feet above the 

 sea, depth 106 feet to 224 feet. " Variable ; often as deep at the margin as in 

 the middle." 



§ About 12^ miles long, 2 wide, 1544 feet above the sea. Depth variable, 

 greatest at the upper end, being 1163 off Unterach and 1282 near the opposite 

 shore (that is, a few furlongs N. of the middle line of the Mondsee valley), 

 933 feet opposite to Schwandt, and 311 feet near Buchberg. 



