94 Observations Concerning Fossil Organic Remains. 
the formation of plastic clay, of molasse and conglomerates 
of various kinds, mtermediate between these strata? In eve- 
ry formation, from the lowest to that which is uppermost, we 
perceive a repetition of rocks and strata, whose chemical 
sly remarkable, A niviing character of the sranaition for? 
mation, and which separates it from the primitive and secon- 
dary (more properly “ tertiary”) is seen in the alternation of 
a series of rocks, in w there is a regular recurrence of 
similar beds, rendering perfectly obvious, likewise, the limits 
of this extensive class of rocks. Another characteristic of 
t 1e three great formations which 
hold near rly the same rank in different parts of the globe ; 
They are, 1st, taleose granular limestone, hee with 
anthracite and mica slate; 2dly, syenite and porp with 
crystals of hornblende, and occasionally quartz ; Cale clay- 
ate, graywacke and black limestone 
e mica slate with anthracite and clay slate serves as the 
connecting points of the transition with the primitive ; whilst 
on the other hand, the fine grained graywackes and por- 
phyries, abounding in the crystals of quartz cause it to ap- 
proximate to the secondar 
The different ages of thas formations are likewise indica- 
ted by their position. For example, the of Guan- 
axuato repose upon a bituminous clay-slate, zee of Hun- 
gary upon a transition mica slate, whilst those of the Andes, 
ae Quito are situated n primitive rocks; large masses 
ore ¢ 
y uniform er decidedly crys- 
. rocks; when we view this 
in the aeemnnitiony still less in 
