TRANSITION AND SECONDARY STKA'J'A. 
90 
bnrrierat tlicir lower CA'Iremitv. A ^renl iiumhorof lakes, istlicre- 
Ibi'e an indication that the refiion in which they lie, has init recenl l\' 
emerged iVoni thcocean, and it isrenuu kahle that thecountrv aroniul 
the Baltic, which is supiiosed to he risiiiii o;radually at tliis time, 
ahounds in them, especially that part of Hnssia which liorderson 
the Gulf of ]5othnin, and heai's the name of Fiidancl. 'J'he south¬ 
ern States being without lakes, it may he infei'red that the era of 
their cmci’gencc is exceedingly remote, at least when compared 
with that of iNIaine, and the other New England States, the ter¬ 
tiary deposits of the seahoaial, of course excepted. 
53. Prop. VII. Since the consoHdulioji dJ' the cryslalline or 
priynitice roct>s, the earth has rnu/eri'oyie a great na7/iher of 
catastrophes and revotat ions, t)y ictiich its face has been c/iang-- 
cd. It is probable that in most cases, if not in alt, the causes 
rf these ynutations in its cniatition enut aspect, were local, and 
their effects confined to an area ef no reri/ great extent. 
O'he transition and sccondaiy strata ai'e made up chietly of the 
rounded fragments and rnins of m'U'e ancient for mat ions, (Sections 
19 and 21.j The conglomerates, sandstones, clay-slates, lime¬ 
stones, and beds of clav and sand of which they are constitutetl, 
do not in themselves ])Ossessany high degree of interest. ]i is to 
theoi'ganic remains they hold imbedded that the attention of ge¬ 
ologists has been ])rincipally directed, especially dui'ing the last 
30 or -lO years, with a view of ascci taining the dillercnt varieties 
of animal and vegetable form and structure that have existed 
upon the earth, and the order of their succession, anil thus arri¬ 
ving at some sound and accurate conclusions res])ccting the con¬ 
dition of the globe itself through a long series of ages, and the 
changes to which it has been sulijected. 'I'he histoi-y of the se- 
condai’y and tertiary strata is tlierefore. to a great extent, the 
history of organic life during the jieriods of their formation. 
If the earth was originally a melted mass, it is e\ ident that 
there must have been a time subsequent to the consolidation of 
the jmimitive rocks, when its tem|/eraturc was such that water 
couhl not exist in a liquid state upon its surface, but the existing 
oceans hung as an atmosjrherc of vajior around the hot and di-y 
skeleton of the globe. To this jieriod must have succeeded 
another, wlien the great mass of the vapor liod been conden¬ 
sed into water—but water not many degrees below the boiling 
point, and in which fe'% animals and vegetables, if any, could 
live. In this condition of things, the vapory and gaseous mass 
surrounding the eai th, would bear a considerable resemblance to 
the now existing atmosphei-e. It ivould be composed ])rinci])al- 
Iv, as at present, of the incondensilde gases, oxygen and nitro¬ 
gen, hut would he highly charged with watery vajiour, and |)ro- 
bablv also with carbonic acid. .Ml the phenomena of meteoroloiiy, 
evaporation, condensation, the wearing away ol the solid j'oeks 
by toi’rents as the rain that iell nmhed down to the ocean, and 
the formation of that mixture of line particles of silica and alumina 
