1882.] 35 [Davis. 



near the centre of glacial dispersion, any broadly continuous gla- 

 cial de230sit ; local terminal moraines dropped as the ice finally 

 disappeared are plentiful though scattered ; but glaciated rocks 

 are always abundant below the upper level of glaciation. On the 

 surrounding lower country there is a complete contrast to this. 

 The bed-rock is generally not glaciated unless it rises in project- 

 ing ridges ; it is covered by old water-^vorn, stratified gravels, and 

 on these are laid the boulder-clay, unstratifieci and with scratched 

 stones direct from the ice. Many sections are known where 

 " interglacial " deposits are preserved undisturbed between a 

 lower and an upper till. 



Necker noticed the occurrence of old gravels (alluvion ancienne) beneath 

 the till (diluvium) near Geneva. (Etudes geol. dans les Alpes, Paris, 1841, 

 232.) 



A. Favre gives further description of the same deposits ; he considers the 

 old gravels washed ahead from the glacier as it advanced. (Recherches 

 Geol. i, 208; Phil. Mag. xxix, 1865, 209; at the bottom of this page, but 

 should he inserted before from the Valais ; later he questions this origin, 

 Soc. Geol. Bull, in, 1875, 658.) 



Falsan and Chantre recognize the general occurrence of gravel under 

 the till of the. Rhone glacier below Geneva ; they explain it as above, and 

 deny erosive power to the ice that moved over it. (Monographic geol. des 

 anciens glaciers du bassin du Rhone. Lyon, 1879-80, n, 65.) 



B. Studer describes the old gravels under the till below several of the 

 Swiss lakes, and decides that the lakes could not have been eroded by 

 glaciers that failed to rub away the gravels. « (De l'origine des lacs suisses, 

 Bibl. Univ. Arch, xix, 1864, 89.) 



Fr. Kinkelin finds the same old gravels between the Tertiary strata and 

 the till east of Lake Constance where the Glacier of the Rhine had a 

 broad extension. (Ueberdie Eiszeit, Senckenberg. Ges. Bericht, 1875, 91.) 



Zittel describes the glacial deposits of the plain south of Munich as rest- 

 ing in great part on loose gravels and seldom reaching to solid rock. (Ueber 

 Gletscher-Erscheinungen in der bayerischen Hochebene, Miinchen, Akad. 

 Sitzungsb, iv, 1874, 264.) 



Penck gives full details for the same region. (Vergletsch. Nord. Alpen.) 



E. Desor calls attention to the necessary contradiction between the theo- 

 ries of glacial erosion and interglacial epochs ; the evidence for the latter 

 depends on the fact that the ice did not strongly erode the surface over 

 which it advanced. (Paysage Morainique, Paris, 1875, 79 — .) 



The so-called interglacial beds of the northern slope of the Alps aro 

 described as follows : — 



