SCIENCE. 



[Vol. XXII. No. 551 



as held and interpreted by the early Fathers, taiight that 

 the world was of a comparatively recent origin, and did 

 not date beyond four or five thousand years before the 

 Christian era, and that the time occupied in the act of 

 creation comprised six ordinary days. 



Geological investigation, however, constrains us to as- 

 sign to the earth an antiquity much more remote than 

 the sis or seven thousand years which it is commonly 

 supposed to have existed, and to give to the several stages 

 which marked its gradual development a limit beyond the 

 twenty-four hours included in each of the successive days 

 of creation. 



It is impossible, however, for us to arrive at any defi- 

 nite conclusion as to the age of the world. Scientists, 

 anxious and zealous in the maintenance of truth, ^ differ 

 among themselves as to the exact time occupied in the 

 various modifications which the world must necessarily 

 have undergone previous to its being occupied as the 

 temporary abode of man. Instead of a few thousand, the 

 space included comprises tens of thousands of years; some 

 estimating the time at fifty thousand, others at two hun- 

 dred and fifty thousand, and half a million of years as 

 being necessary to the production of the present condi- 

 tion of things. But in one particular they all agree, and 

 unite in giving to the earth a place in history many thou- 

 sands of years anterior to the creation of man. 



The rocks of which the earth's crust is composed are 

 divided into 1st, igneous, or eruptive and unstratified 

 rooks, and 2d, aqueous, or sedimentary and stratified 

 rocks. 



A third division is sometimes made and designated as 

 metamorphic rocks, or rocks of a stratified crystalline 

 formation, which in reality are only sedimentary rocks 

 which have been changed by the action of steam or heat 

 without destroying their stratified appearance. 



By far the largest proportion of the earth's crust with 

 which the geologist has to do is composed of aqueous or 

 sedimentary and stratified rocks, and to the stiidy of these, 

 principally, must we look for those facts and data which, 

 without doubt, prove our world to have a history of very 

 great and undetermined antiquity. 



By the crust of the earth is to be understood the mate- 

 rials of these several great sub-divisions of which the 

 earth's surface is composed. It is by no means to be re- 

 garded as a solid mass throughout. Different theories 

 have been advanced by scientists in reference to the in- 

 ternal condition of the earth. 8ome consider the centre 

 of the earth to be composed of rock matter solidified by 

 pressure with liquid fiery matter between this central 

 area and the crust on the surface. 



Others regard the earth as more or less solid, with lakes 

 and seas of fire internally alternating throughout, while 

 many others, and the commonly received opinion, hold 

 that beneath the surface, of which we are accustomed to 

 speak as the crust of the earth, and which extends to only 

 a very limited depth, the whole of the internal portion of 

 the earth consists of a molten sea of liquid fire. 



The evidence in favor of this is confirmed by the fol- 

 lowing observations: In various parts of the world and 

 at certain depths below the surface, an even temperature 

 is found to exist throughout the year. At greater depths 

 the temperature invariably increases, and although in all 

 places it is not uniform, owing to the different kinds of 

 rock jpenetrated, the average rate of increase is one de- 

 gree for every sixty feet. And, as we may reasonably 

 suppose the ratio to increase the greater the depth at- 

 tained, we might expect comjsaratively soon to reach a 

 temperature sufliciently high to sustain most minerals in 

 a vaporous or molten condition. 



Another evidence is found in the fact, that water 

 brought at great depths from beneath the su.rface is 



found to possess a higher temperature than the temjiera- 

 ture of the surrounding locality, and if the depth be ex- 

 tended the tem}Derature of the water is increased with it. 



Another and more convincing argument in proof of the 

 molten condition of the interior of the earth is aiforded 

 us by the numerous volcanoes which occur throughout 

 the world, some of which have been in active operation 

 for hundreds, and even thousands, of years. They are 

 generallj' regarded as constituting the principal channels 

 of communication between the interior parts of the earth 

 and the surface; and from unfathomable depths are more 

 or less constantly pouring forth immense volumes of mol- 

 ten rock and liquid streams of living fire. More than 

 two hundred and fifty volcanoes are now known at differ- 

 ent times to be in a state of eruption, and many others 

 have long since ceased to exhibit any degree of activity. 



The thickness of the earth's crust has been variously 

 estimated at from ten to twenty miles and upwards, but 

 there is no means by which the exact depth of rock matter 

 upon the surface can be accurately determined. 



From the above considerations we are led to the conclu- 

 sion that the interior of the earth consists of a mass of 

 igneous incandescent matter, and which may have been, 

 originally, the condition of the material now forming the 

 crust of the earth, and that the gradual cooling of the 

 surface by radiation, accompanied by the shrinkage and 

 contraction attending the cooling process, together with 

 the enormous j)ressure from within, jjroduced immense 

 crackings and bulgings of the earth's crust, which result- 

 ed in the many groups and chains of mountains, and asso- 

 ciated valleys, to be seen upon the surface. 



The rocks surrounding Lake Nij)issing belong to the 

 oldest known rocks in existence. They are the lowest 

 and first in the order of sequence, and with but one ex- 

 ception, so far as is known, are almost entirely of an erup- 

 tive or metamorphic origin. They belong to the great 

 Laurentian formation which extends over all the northern 

 portions of the provinces of Quebec and Ontario, and con- 

 tinues west and northward to the Arctic Ocean. They 

 are usually distinguished by theii- inclinatioil at high 

 angles, and by presenting in many places a variously 

 folded and contorted appearance, and by the absence of 

 organic remains. Here and there thej' are broken 

 through by fragments and hugh masses of granite, which 

 in some instances appear to have become the centres of 

 eddies or whirlpools of molten rock. Some very interest- 

 ing examples of these may be seen on the high, rocky 

 portion crossed by Mclntyre Street in the southeast part 

 of the town of North Bay. 



During some period of the world's history this whole 

 region has undergone a most terrific convulsion of up- 

 heaval and depression, during which streams and lakes 

 of fire appeared upon the surface, liquefying and chang- 

 ing the condition of the rock masses with which they 

 came in contact. 



To this same jDeriod, and to the operation of these 

 same agencies, must we trace the origin of the extensive 

 mineral deposits which occur throughout this northern 

 region. The various metals being more fusible than the 

 rock masses in general, found a ready exit in the cracks 

 and fissures formed by the breaking of the earth's crust, 

 and filling these became subsequently cooled, forming- 

 veins of various dej^ths and thicknesses, and sometimes 

 extending for miles in length, imparting to this part of 

 our dominion, in outward apjaearance so uninviting, an 

 attractiveness of wealth, in mineral resources, unrivalled, 

 and perhaps it would not be an exaggeration to say, un- 

 equalled by any country in the world. 



The rocks forming the second great sub-division into 

 which the crust of the earth is divided are called aqueous, or 

 sedimentary rocks. They are essentially formed by the ac- 



