40 W. UPHAM — giants' KETTLES ERODED BY MOULIN TORRENTS 



one of the chief attractions of sight-seers in lAicerne, Switzerland. This 

 town, visited by the writer in 1897, is in manj^ respects the most fascinat- 

 ing one for tourists in the Alps, and the most convenient for nian}^ neigh- 

 boring excursions, as to mounts Rigi and Pilatus, and the sail on the 

 wildl}^ picturesque and historic Lake of the Four Forest Cantons. The 

 Glacier garden, containing the giants' kettles, is about 100 feet above 

 the lake, and is only a few stei)S from the Lion monument, designed by 

 Thorvaldsen, which was chiseled from the solid rock fifty 3^ears earlier 

 (in 1821). Thirty-two potholes of moulin torrent erosion are counted 

 in the garden, occurring irregularly grouped upon a remarkabl}^ furrowed, 

 waterworn, and glacially striated rock area about eight rods long and 

 four rods wide, which was originally so drift-covered that its wonderful 

 torrential and glacial sculpture was concealed. Tlie covering of soil and 

 drift has been removed since 1872, and many rounded stones, which 

 served as grinders rapidly whirled around by the falling waters, from 

 those of small size U]) to others of huge dimension, five feet or more in 

 diameter, have been removed with the gravel, sand, and clay that filled 

 these rock kettles. 



The largest i)othole of Lucerne, on the northwest border of the group, 

 has a diameter of 26 feet and depth of 31 feet. Its southern side over- 

 hangs, ])robably because the northwardly flowing current of the over- 

 lying glacier carried the moulin slightl}^ forward while the rock erosion 

 was taking place. The movement was least at the base of the glacier, 

 and increased differentiall}^ upward. The moulin therefore became in- 

 clined, and discharged its torrent somewhat backwardl}" into the rock 

 kettle, hollowing it thus with an overhanging wall. The same feature 

 is observable in others of these i)otholes, and several of them display 

 spiral wearing. In some instances the potholes have irregular and 

 composite forms, showing apparently that successive and independent 

 moulins, probably of diflerent years, contributed to their erosion. The}' 

 range in size from the largest to others 9 or 10 feet deep and 4 or 5 feet 

 in diameter, and to small cylindric or hemispherical kettles onl}^ 1 or 2 

 feet deep. 



It is also to be noted that the rock at two or three places is waterworn 

 in broad and somewhat crooked grooves, varying in depth to 6 or 7 feet, 

 and extending 20 or 30 feet in length, where the moulin torrent was less 

 concentrated and more variable than usual ; or, more probal)l3^ these 

 grooves may have been made by a very inclined and powerful englacial 

 and subglacial stream there impinging on the rock floor. Perpendicu- 

 lar potholes of the usual form, but of small size, occur occasionally in 

 the grooves. It is especially noteworthy, both here and in other local- 

 ities of Europe and America, that generally the edge or lip of the giants' 



