I^rof. Necker on the History and Progress of Geology. S27 
which he has explored have presented only infinite varieties in 
the mineralogical order of the rocks, with relation to the physi- 
cal structure of the chain ; all this finds a ready explanation 
(and those w^ho are acquainted, with the nrlneralogical geogra- 
phy of Europe will be convinced of it), in the circumstance, that 
there is no country less adapted for the regular study of forma- 
tions than the chain in 6ur neighbourhood, and which is itself 
only a small portion of the vast geognostical system v/hich may 
be denominated the Chain of the Alps. 
An inconsiderable number of different formations occupy 
there a prodigious space ; the strata of which they are composed 
present gigantic masses, and their structure assumes such a de- 
gree of development, that mere subordinate beds cover a much 
greater surface than elsewhere whole independent formations. 
Add to this- the irregularity in the position of the strata, 
their numerous and enormous contortions, the absolute want of 
relation between the mineralogical and the physical structure of 
this portion of the chain, and say if it was possible, for even 
the greatest genius left to itself, to discover that regularity in 
the order of succession of formations which has been traced in 
other countries, in characters so clear and so easily accessible ; 
since, even at the present moment, with all the perfection to 
which geology has attained, and, notwithstanding the great 
number of expert observers who have travelled among the Alps, 
we have not yet discovered the key of the enigmatic arrangement 
of the formations of which they are composed. 
But, if we consider the list of agenda which concludes his 
works, we shall there see exposed, under the form of questions, 
all the most important positive or negative results to which the 
study of the Earth should lead. Without doubt, the great im- 
provements which have been made in the science, would require 
the addition of a considerable number of questions ; without 
doubt, also, several of these problems have been resolved by the 
illustrious author, or by his successors ; but the greater number 
still require to be answered ; and these agenda, although pub- 
lished thirty years ago, should still, at the present day, form an 
indispensable guide to him whose object is to pursue the study 
of geology in its full extent. They have marked -out all the 
routes which should be travelled by him who wishes to embrace 
