4 
THE FORMATIONS OP WHICH THE GLOBE IS COMPOSED. 
and the observation has been confirmed, the 
heat being determined to be 11^ 82 (53^* F.) 
Cordierhas inferred from his researches on 
the temperature towards the interior of the 
earth, that below a particular point where 
the temperature is steady, the heat increases 
with the depth, to the amount of P for every 
25 to 30 metres. 
M. Fourier lias demonstrated that the cool- 
ing of the globe, i/s«c/r a fact is admitted, 
must be very slow, being less than 
of a centigrade degree for a century ; and 
he has drawn these consequences: 1. All 
the heat below a particular point where the 
temperature is steady, has been possessed by 
the earth from its commencement. 2. This 
heat is intense in the nucleus, and at a cer- 
tain distance from the centre it begins to di- 
minish by regular laws up to the steady point, 
3, d'he internal equilibrium changes with 
time, and will continue to alter until the 
whole heat is dissipated, but this process is 
going on in an extremely tardy manner. 4. 
The heat derived from the interior cannot 
appreciably modify that of the surface. 
Idumboldt has observed that in Mexico 
the decrease of temperature is not pi’bpor- 
tional to the height ; and Boussingault has 
found that in twenty-three years the sources 
of the Mariara have increased in tempera- 
ture from 59° 3 C, to 64° ; and those of Strin- 
cheras, from 4 to 92° 2, The diurnal 
variation of the thermometer at the equator 
on the sea is 1° to 2°, while on the continent 
it is 5° to 0°. At the equator the ocean’s sur- 
face is hotter than the air ; but at the poles 
the reverse is the case.* Between the tro- 
llies, the heat diminishes with the depth; on 
the polar seas it diminishes as we descend. 
Such are some of the principal circum- 
stances bearing upon terrestrial heat with 
which we are at present acquainted. 
THE FORMATIONS OF WHICH 
THE GLOBE IS COMPOSED is the next 
subject which our author takes up, after spe- 
culating upon the method in which it was 
consolidated, applying known agents to the 
explanation of volcanic phenomena, and 
tracing out a sketch of the facts which have 
been ascertained in reference to terrestrial 
heat. He first notices alluvial deposits which 
are in process of formation, consisting of peat, 
marls, graval, stalactities, pisolites, and tra- 
vertines. He then passes to mineral waters 
or salt springs, which are so influential in 
bringing up from considerable depths soluble 
salts. In these are found carbonate of soda, 
borax, alum, deposited in the fissures of rocks, 
nitrate of soda as in Peru, nitrates of potash, 
lime and magnesia, as in Hungary, Ukraine, 
Podolia, &c.; sulphate of magnesia, sulphate 
and carbonate of lime. These substances 
seem to be deposited by the water when tra- 
versing fissures of rocks, and which action is 
more energetic in proportion to the increase 
of temperature. The quantity of salts brought 
by these means is much greater than one 
* In lat. 28 9' N., long. 20a 33 W-, I found the 
temperature of the Atlantic Ocean 79°5, that of 
the air being 79® ; and in 2-20 S. L., 59 ^ 5 ' E. L. 
the thermometer stood in the air at 80°, and in 
the Indian Ocean at 88«6, — Edit. 
\vithout consideration would infer. The 
Carlsbad water discharges annually 740,884 
pounds of carbonate of soda, and 132,923 
pounds of sulphate of soda, in addition to 
numerous other substances. Now, the ope- 
ration of solution must be effected by the 
electro-chemical action of the thermal waters 
upon the rocks, at a greater or less distance 
frorn the earth’s surface, 
fl he origin of the ocean’s saltness has at- 
tracted the attention of many, but little light 
has been hitherto thrown on this subject. It 
IS, however, apparent, that the quantity of 
saline matter varies on account of the proxi- 
mity of rivers ; thus, the Baltic and the Black 
Sea are weaker than the occean, and still 
more so than the Mediterranean. 
From Boussingaull’s observations, it appears 
that the temperature of hot springs diminishes 
with the height; and hence he infers that 
they have their origin in the volcanic fires. 
He found that the mineral waters near volca- 
noes contained sulphuretted hydrogen and 
carbonic acid, the identical gases which were 
detected among the vapours emitted from their 
corresponding volcanoes. The carbonic acid 
he considers as the product of the calcination 
of carbonate of lime and soda, or of their re- 
action upon silicious or aluminous substances, 
and the sulphuretted hydrogen may derive its 
origin from the re-action of the vapour of 
water upon sulphui’et of sodium. 
The rocks of the tertiary formations are in 
general calcareous and silicious with a pre- 
dominance of magnesia, especially where the 
gypsum appears. Under this head are in- 
cluded the new formations characteidzed so 
happily by Air. Lyell, and to whose work it is 
proper to refer the reader for accurate and 
interesting information. 
The secondary rocks include the chalk, 
which is the result of chemical precipitation, 
the oolites, a sedimentary group, as well as 
the muschelkalk and zechstein. 
In the ti'ansition rocks, the coal, according 
to Deluc, has been foi’med at a slight eleva- 
tion above the sea like turf, and has been 
submer ged and covered by the sand of the 
ocean. If these waters are supposed to 
Imve borne along with them earthy matter 
of an elevated temperature, an explanation 
will be afforded for the absence o f animals in 
these rocks. The water under which the 
coal was formed must have possessed the 
property of holding iron in solution, as is ap- 
parent from the quantity of iron-stone which 
usually accompanies coal. Hence, the 
atmospheric pressure may have been greater’. 
The formations which derive their origin from 
the greatest depths, are obviously granite, 
mica slate, and the rocks usually termed pri- 
mary. The porphyries, euphotides, or com- 
pounds of jade and diallage, serpentines, 
black porphyry, or ophites and dolomitess, are 
more variable in their position. 
Among volcanic products the trachites are 
considered most ancient, and are sometimes 
startified. The traps, or basalts afford many 
minerals; the lava group contain also many 
species. Both HStna and Vesuvius have 
been known to eject granite, in addition to 
the pulverulent and solid matter which they 
continue to emit at intervals. 
