96 Kansas AcadeTny of Science. 



of the ice when the glacier becomes stagnant. It forms a 

 superglacial sheet quite analogous to the lower till already- 

 described. How much of it is englacial and how much is 

 superglacial is still in doubt, but that it was formed both by 

 englacial and superglacial agencies there is an abundance of 

 evidence. 



Medial Moraines. — These merge into dump-moraines at 

 the frontal edge of the ice, and into upper till in cases in 

 which they are let directly down by melting without being 

 carried on to the terminus of the glacier. They are very sub- 

 ordinate elements in the great Pleistocene glacial deposits. 



Lateral Moraines. — Moraines of this type formed along 

 the sides of the glaciers. They are composed of sands, grav- 

 els and boulders, the boulders being the prominent constituent, 

 whence the name "boulder train" which is often applied to 

 this moraine. They are formed by the edges of the ice-sheet 

 rubbing along the sides of the valley through which it travels, 

 forming lateral embankments. 



Medial Lateral Moraines. — These are moraines formed 

 by the junction and coalescence of two glaciers. 



Intermediate or Interlobate Moraines. — These are 

 formed by the front action of two glacial lobes pushing their 

 marginal moraines together and producing a common moraine 

 along their line of contact. They are terminal moraines in 

 character, but intermediate, or interlobate in position. 



Terminal Moraines. — Any special aggregation of drift 

 along the margin of a glacier is a terminal moraine. 



Peripheral Moraines. — A peripheral moraine is a moraine 

 of the terminal type which marks only a temporary halt or 

 insignificant advance of the ice-sheet. 



Remarks on Morainic Structure and Material. — Considered 

 in respect to its internal constitution, the morainic formation 

 is distinguishable into several distinct portions: The one, 

 usually the uppermost but not occupying the heights of the 

 range where it has its best development, consists almost 

 wholly of assorted and stratified material. The other element 

 of this formation, and the one which constitutes its basal por- 

 tion and its great core when developed under favorable con- 

 ditions, consists of a confused commingling of clay, sand, 

 gravel and boulders of the most pronounced type. There is 

 every gradation of material, from boulders of many tons 



