CHARACTERISTICS AND DISTRIBUTION OF LAKES 595 
open outlet, but the waters escape by an underground passage and 
reappear above Vallorbes, whence they flow to the Lake of Neuchatel. 
Lakes of JOUX and Brenet together cover an area of 3^ square 
miles, and lie at an elevation of 3307 feet above sea-level. The 
maximum depth is 112 feet, and the mean depth 59 feet. 
Many small lakes in the Jura Mountains occupy troughs formed by 
downfolded strata, and the Lake of Joux is marked at its north-east 
end by a strong cross fault. ^ 
Lake of Neuchatel (or Neuenburger See) lies at an elevation 
of 1417 feet above sea-level, and covers an area of about 85 square 
miles. Its greatest depth is 505 feet, its mean depth 210 feet, and it 
is estimated to contain about 500,500 million cubic feet of water. It 
occupies a synclinal valley, as do also the Lakes of Brenet and Morat. 
It is surrounded by marshes, which used to cover about 50,000 acres, 
but a good deal of that area has now been drained. At one time the 
Lake of Neuchatel formed a single sheet of water with the Lake of 
Bienne, and extended from Orbe on the west to Soleure on the east. 
Guyot considers the Lake of Neuchatel the result of local depression.^ 
Lake of Bienne (or Bieler See) lies at an elevation of 1417 feet 
above sea-level, and covers an area of 17 square miles. It has a 
maximum depth of 249 feet, a mean depth of 92 feet, and its volume 
is estimated at about 43,800 million cubic feet. 
Lake of Morat (or Murten See) lies about 1427 feet above sea- 
level, and covers an area of 10| square miles. Its maximum depth is 
157 feet, its mean depth 72 feet, and it is estimated to contain about 
21,200 million cubic feet of water. It drains into the Lake of 
Neuchatel by the River Broye. 
The River Suhr drains the Lake of Sempach, and joins the Aar 
below Aarau. The valley it occupies is out of all proportion to the 
size of the present river, which has excavated its channel entirely in 
glacial deposits. Hence this valley and others of a similar descrip- 
tion are attributed by Kaufmann ^ and Gremaud ^ entirely to glacial 
action. The glacier which came down the valley of the Suhr is 
supposed by Kaufmann to have been obstructed by the hill of Wohlen, 
and the pressure of the ice caused by this obstacle may account for the 
depression now occupied by the Lake of Sempach, which is dammed 
by the moraine. 
Lake of Sempach lies about 1663 feet above sea-level, and 
covers an area of 5 J square miles. It has a maximum depth of 285 feet, 
^ See Sheet XI,, Swiss Geol. Commission. 
2 M^m. Soc. Sci. Nat. Neuchatel, t iii., No. 6, 1845. 
^ Beitr. z. geol. K. d. ScJuu., xi., 1872. 
Gremaud, " Quelques donnees siir les vallees primitives et les vallees d'erosion 
dans le canton de Fribourg," Bull. Soc. Fribourgeoise Sci. Nat, Ann.v.-viii. p. 25, 1888. 
