Vol. XXIV. No. 9.] 
POPULAR SCIENCE NEWS. 
131 
[Original iu Popular Science yews.] 
GEOLOGICAL FORMATION OF THE EARTH 
— ITS EVOLUTION FROM CHAOS TO 
ORDER. 
BY JOSEPH WALLACE. 
In this article we have given the readers of Popu- 
lar Science News an outline of the geological 
development of the earth's crust, the successive 
strata and fossils of the different systems of forma- 
tion, and a summary of the classes of animals and 
plants which have existed in their respective ages. 
Knowing well the objection of Popular Science 
News to serials, and knowing the impossibility 
of giving in a limited space the desired information 
demanded by such subjects, we must necessarily 
treat our subjects singly and independently to make 
them interesting and instructive. 
Geology would be barren and almost useless 
without the aid of paleontology. In one sense, it 
may be regarded as a branch of zoology and botany, 
while its claim in this view to rank as a separate 
science is resting on the fact that, of the forms 
with which it treats, a small proportion belongs 
to the living world ; in another sense, It may be 
regarded as a branch of geology, seeing that its 
assistance is absolutely indispensable in many of the 
-most familiar and fundamental problems of the 
latter science. In its pfopef sphere, it is a science 
which treats of the structure, affinity, classification, 
nnd distribution in time of the forms of animal 
■'ind plant life imbedded in the rocks of the earth's 
irust. It is as a branch of geology we have to 
regard it here, because without the leading features 
of paleontological inquiry, progress in modern 
geology would be impossible. 
The first class of the lowest rocks are those resting 
next to the primitive rocks, — gneiss, mica schist, 
nnd chlorite slate, — in which no fossils are found. 
The eozoon canadense, discovered in these rocks, is 
generally considered a being of no organic nature, 
tiLcauKC, by common consent, It is supposed. such 
deposits took place at a time when there Was no 
organixed being upon earth ; therefore) these forma- 
tions belong to the Azoic or Eozoic period, and 
c.iUed as such. This is the first period of the 
earth's formation ; the first adopted system of ancient 
*iietamovphic rocks of Scandinavia, Canada, etc. ; 
first (n the class of eozoon, and probably other pro-- 
to«oa; first in graphite and iron ores, representing 
vegetable matter. It is proper to state here that 
many geologists and naturalists doubt the organic 
nature of eozoon. 
The fossiliferous strata are denominated Paleozoic, 
lesozoic, 4nd Cainazoic Ages, that is, formations 
belonging to the older, middle, and modern periods 
•of "oifgnnic life on earth. These four periods are 
iaUo called Archaeolithic, Paleolithic, Mesolithic, 
and Cainolithic. The formations made from depos- 
its in the historical period may be reckoned as 
a fifth class — those of the Recent Age, including 
coral islands, river deltas, sand hills, deposits 
of calc-stnter, turf beds, etc. 
Second : Primary or Paleozic period. — Embraces 
first the Cambrian system of formation ; classes 
of animals and plants as follows : radiata — of this 
there are the hydrozoa, echinodermata (cystideans) ; 
mollusca — brachiopoda, lamellibranchiata, gaster- 
•opoda, cephalopoda (bivalve and univalve shell- 
ifishes) ; articulata — annelida, Crustacea (worms and 
•soft shell fishes of the lowest grade.) Lower Silu- 
:rian system : radiata — anthozoa (coral animals), 
•echinodermata (sea stars, etc.) ; mollusca — polyzoa, 
tunicata, and other mollusks and articulata as] 
mentioned before; plant* — algie: Upper Silurian:! 
radiates, mollusks, and articulates as before; verte-! 
brata — first ganoid and placoid fishes. Erian or! 
■Devonian: .ar.tipulata— insects and higher cn,isjta-I 
ceans; vertebrata — fishes, ganoid and placoid; 
plants — acrogenous land plants, acrogens and gym- 
nosperms. Carboniferous: mollusca — pulmonta 
(land snails) ; articulata — myriapods, arachnidans, 
gally-worms, spiders, and scorpions; vertebrata — 
batrachians or amphibians prevalent. Permian : 
vertebrata— lacertian or lizard-like reptiles. Tri- 
assic : vertebrata— higher reptiles prevalent, mar- 
supial mammals; plants — acrogens, gymnosperms, 
endogens (.') 
Third : Secondary or Mesozoic period.— Jurassic 
formation : vertebrata — great prevalence of higher 
reptiles, fishes, homocerque, earliest birds. Creta- 
ceous : vertebrata — decadence of reptiles, ordinary 
bony fishes ; plants — endogenous trees, angiosper- 
mous exogens. 
Fourth : Tertiary or Cainozoic period. — Eocene 
and Pliocene formations: vertebrata — mammals 
prevalent (especially p.ichyderms), cycloid and 
ctenoid fishes prevalent, first living invertebrates; 
during the Pliocene period living invertebrates 
more numerous; plants — exogens prevalent, also 
some modern species appear. 
Fifth : Post Tertiary or Modern period. — Post 
Pliocene, Post Glacial, and Recent formations : first 
living mammals, living invertebrates prevalent, 
man and living mammals ; plants — existing vegeta- 
tion. 
This concise tabular view is mainly from Dr. 
Dawson's work. Origin of the World. It gives an 
idea of tlie arrangement at present generally re- 
ceived, with some of the more important facts in 
the succession of animal and vegetable life. It 
begins with the oldest periods known to geology, 
gives the animal and vegetable kingdoms, and first 
appearance of each class, with a few notes of the 
subsequent history of the principal forms. It must, 
however, be borne in mind that further discoveries 
may extend some classes further back than we at 
present know them. 
The great mass of unstratifled rodks which under- 
lie the stratified ones are supposed to be the oldest 
portion of the earth's surface. They are found in 
parallel layers, but occur irregularly in their strati- 
fication and succession, under, among, and above 
the stratified rocks ; and these are therefore called 
primitive. It is generally supposed by geologists 
that the stratified rocks which are found in parallel 
layers superposed above them were gradually depos- 
ited by water. Werner called this part of the earth's 
surface the "sedimentary rocks," in contradistinc- 
tion to the primitive rocks, which are always found 
below them, and alluvial soil, always above them. 
The lowest rocks — -that Is, those sedimentary rocks 
which He next to the primitive — he calls " transition 
rocks." He divides the other sedimentary rocks 
into the older, middle, and recent formations. 
The rocks lying on the primitive strata are 
divided by others into three groups : transition 
rocks, with one or two of the formations lying 
nearest to them, are called "primary;" the greater 
portion of the sedimentary rocks, "secondary;" 
and the strata nearest to the surface, "tertiary" 
rocks. For the present we may omit other names 
and divisions to avoid confusion. Each of these 
principal divisions contains several sub-divisions, 
which are called by different names, mainly on 
account of their constituent parts, as coal formation, 
chalk formation, etc. ; lias formation, which is the 
English name for a kind of limestone ; triassic 
formation, because it always consists of three com- 
ponent parts— keuper, muschelkalk, and red sand- 
stone, or "hunter sandstein ; " and some partly from 
the places in which they were found, as, for instance, 
Silurian formation, named from the district in the 
■"vVest of F;ngland which it is supposed the Silures 
inhabited at' the time of the Romans ; Devonian 
formation, so called from Devonshire, England ; 
Permian formation, from the Russian province 
Perm; Jurassic formation, from the Swiss mountain 
Jura, and so on. 
One of the principal tasks of geology was to 
define, at first, the limits of the separate formations, 
and (hen to determine their relative age; also to 
discover especially which of the different strata are 
parallel to each other in different regions, that is, 
which probably belong to the same period. In 
order to accomplish this, it was first necessary to 
ascertain the materials of which they are composed, 
the order in which they are deposited, and after- 
wards the examination of the fossils which were 
found in them; finally, this last point has been 
especially considered, and proves a valuable aid to 
geology. 
In regard to the relative age of fossils, although 
absolute dates cannot be found in geological chro- 
nology, it is not difficult to determine the relative 
age of different strata, and consequently of their 
enclosed organic remains. For this purpose the 
fundamental law is based on what is termed the 
"order of superposition." This law may thus be 
defined : In a series of stratified formations the 
older must underlie the younger. Rare instances 
occur where strata have been so folded by great 
terrestrial disturbance that the younger are made to 
underlie the older; but this inversion can usually be 
made quite clear from other evidences. The true 
order of superposition is decisive of the relative 
ages of stratified rocks. 
The term fossil is defined as follows ; An organ- 
ized fossil body is one which has been imbedded in 
the earth at an unknown period, which has been 
thus preserved, or which has left the unequivocal 
traces of its existence. This excludes from the 
term the modern remains of plants and animals, 
which have been buried and lost by floods, land- 
slides, or accidental causes of our times. This 
definition being adopted, it is easy to fix the limits 
of paleontology. 
FERTILIZATION OF CYPRIPEDIUM 
CALCEOLUS. 
Opportunities having been given me of observ- 
ing a fine half-wild growth of the above plant in my 
neighborhood during the past two years, a note 
of results might be interesting, I thought. • 
As to the growth of one plant since last April. 
From the first appearance of the bud above ground 
it looked remarkably healthy. In seven days it had 
grown two inches, in another seven days it was 
four and one-half inches high, and the leaves were 
opening out. On the twenty-first day it was seven 
inches high with leaves fully developed and flower 
bud visible. On the twenty-eighth day it was 
eight and one-half inches high, and on the thirty- 
fifth day the plant seemed to be fully developed and 
had grown to the height of eleven and three- 
quarter inches, this last rapid growth occurring 
during very favorable weather. The flower was now 
half open, and after coming to perfection lasted 
about three weeks. 
The fertilization of this orchid, like some others 
of the same order, such as Epipactis latifolia, 
Cephalanthera grandiflora, and the Listeras, is 
highly intere ting and somewhat complicated, and 
after careful observation in the matter one has to 
come to the conclusion thaf this, like Epipactis 
latifolia and others, to make up for imperfect 
fertilization has the power of reproducing itself in 
a more certain manner, viz., by increase of the 
root, for it certainly does increase rapidly when in 
favorable situations, even in Britain. 
That the plant is entirely reproduced by insect 
agencies, as was inferred by Darwin and others, is 
