Page:Keil and Delitzsch,Biblical commentary the old testament the pentateuch, trad James Martin, volume 1, 1885.djvu/46

 clearly and fully known, or if the different formations were always found lying in the same order, and could be readily distinguished from one another. But with regard to the origin of the different species of rock, geologists, as is well known, are divided into two contending schools: the Neptunists, who attribute all the mountain formations to deposit in water; and the Plutonists, who trace all the non-fossiliferous rocks to the action of heat. According to the Neptunists, the crystalline rocks are the earliest or primary formations; according to the Plutonists, the granite burst through the transition and stratified rocks, and were driven up from within the earth, so that they are of later date. But neither theory is sufficient to account in this mechanical way for all the phenomena connected with the relative position of the rocks; consequently, a third theory, which supposes the rocks to be the result of chemical processes, is steadily gaining ground. Now if the rocks, both crystalline and stratified, were formed, not in any mechanical way, but by chemical processes, in which, besides fire and water, electricity, galvanism, magnetism, and possibly other forces at present unknown to physical science were at work; the different formations may have been produced contemporaneously and laid one upon another. Till natural science has advanced beyond mere opinion and conjecture, with regard to the mode in which the rocks were formed and their positions determined; there can be no ground for assuming that conclusions drawn from the successive order of the various strata, with regard to the periods of their formation, must of necessity be true. This is the more apparent, when we consider, on the one hand, that even the principal formations (the primary, transitional, stratified, and tertiary), not to mention the subdivisions of which each of these is composed, do not always occur in the order laid down in the system, but in not a few instances the order is reversed, crystalline primary rocks lying upon transitional, stratified, and tertiary formations (granite, syenite, gneiss, etc., above both Jura-limestone and chalk); and, on the other hand, that not only do the different leading formations and their various subdivisions frequently shade off into one another so imperceptibly, that no boundary line can be drawn between them and the species distinguished by oryctognosis are not sharply and clearly defined in nature, but that, instead of surrounding the entire globe, they are all