THE MASSIF OF MONT BLANC. 
lOI 
Figs. 94 and 95 (p. 78), adapted from Mr. Cadell’s 
experiments on the foldings of compressed layers of 
clay, illustrate the structure of the Central Massives; 
that on the right giving the “fan” structure, while 
that on the left shows an overthrust, and suggests a 
possible explanation for the absence of the Crystalline 
Schists in some places on the south of the range. 
Carboniferous strata occur on both sides of the 
Arve, from Servoz almost to I.es Houches, and ex- 
tend eastwards in two bands — one from Servoz to- 
wards Mont Buet, the other from below Argcnti^re 
over the Col des Montets down the Trient to Ver- 
nayaz, and across the Rhone to the Mont de fully. 
The broad valleys of Chables and of Liddes are also 
due to the comparative destructibility of the An- 
thracitic shales belonging to this period. 
The three principal representatives of the Car- 
boniferous strata are (i) argillaceous schists, frequently 
containing vegetable remains; (2) micaceous sand- 
stones, which often much resemble some of the 
Crystalline Schists; and (3) the remarkable con- 
glomerate known as the Puddingstone of Valorsine. 
This Puddingstone consists of rolled pebbles and 
blocks, sometimes over a foot in diameter. These 
must have been brought down by torrents much 
resembling the Alpine torrents of the present day. 
