410 



MINERALOGY. 



Geognosy. The great beds of gravel, sand, clay, marl, &c. which 

 rest on the rocks of the preceding classes, form a class 

 named alluvial. They contain abundance of organic 

 remains, and even of animals at the top of the zoolo- 

 gical scale. Those rocks, which are undo-ibted pro- 

 Volcanic ductions of fire, are named volcanic, and form the fifth 

 rocks. and last class of the series of mountain rocks. They 

 are often posterior to secondary rocks, and sometime* 

 even to substances of the alluvial class. 



Werner, as indeed appears from what has been al- 

 ready stated, seems to consider all the mineral forma- 

 tions as formed by one and the same solution, which 

 has gradually changed in height and in nature. But 

 he saw that this explanation would not apply to every 

 case: for example, if every rock, or bed, should occur 

 at a height corresponding to its age, that is at a higher 

 level in old than in new rocks, how does it happen that 

 porphyry, resembling those in primitive regions, rests 

 upon secondary rocks, and attains a great elevation ? A 

 simple oscillatory movement, Werner remarks, would 

 not explain this arrangement. It follows, therefore, 

 according to Werner's principles, that a new tolution 

 must have invaded the district already abandoned by 

 the old solution, and deposited the newer formations. 

 Werner admitted these new inundations, and attribut- 

 ed to them some particular formations, such as the se- 

 condary trap rocks, and certain primitive porphyries. 

 On Forma- Werner remarks, that when we view the various de- 

 tioni. positions from the earliest discoverable period to the 

 newest, we find in them such differences, as shew that 

 the contents of the water of the globe must have chang- 

 ed by degrees, and that all its depositions form beauti- 

 ful and connected series. The oldest rocks, which are 

 pure chemical precipitates, are composed principally 

 of siliceous, argillaceous and magnesian earths. The 

 rocks, as granite, gneiss, and mica-slate, contain metals 

 that are of cotenaporaneous formation with them, and 

 that scarcely occur in newer periods; these are tin, 

 molybdena, and tungsten. 



This state of the water of the globe, however, alters 

 gradually and remarkably, as we approach the newer 

 periods, by the appearance of limestone in quantity, 

 coal, and salt, and the disappearance of old and the ap- 

 pearance of new metals. Besides this general succes- 

 sion, (which will afterwards be particularly considered,) 

 discoverable in the productions of different periods, we 

 have instances of the repetition of certain products at 

 considerable intervals, and in formations of different 

 aras and kinds. In a series of this kind, all the mem- 

 bers have general characters of agreement, and the in- 

 dividual members bear characters expressive, not only 

 of the period of their formation, but also of the circum- 

 stances under which they were formed. Such a series, 

 as we have already mentioned, is denominated a Prin- 

 cipal Formation Suite, or Series of Formations. By con- 

 trasting the old and new members of such a series, the 

 difference will be found so great, that we can with dif- 

 ficulty recognize them as members of the same forma- 

 tion suite : on the contrary, the immediately preceding 

 or following members are so much alike, that it is 

 equally difficult to distinguish the one from the other. 

 This shews how much the prevailing circumstances 

 that existed during the time of their formation, were 

 alike in the members of the same age, and differed in 

 those of a different date. 



We shall now illustrate this subject by a short abstract 

 of Werner's descriptions of several of these series of 

 formations. 



1. Limestone Formation-Suite. 



* "" 



The first member of this series, is the white granular V' 

 limestone, which occurs in primitive rocks, as gneiss, 

 mica-slate, and clay- slate. This limestone has large 

 granular distinct concretions ; but in the newest clay- 

 slate, the concretions become more minute, and it even 

 approaches to compact. The trrnsition rocks contain 

 the second member of this series, the variegated lime- 

 stone, which has less translucidity than the preceding, 

 but more than the following members of the series, 

 and shews the first traces of petrifactions. The follow- 

 ing, or floetz-rocks, contain the third member of the 

 series, the grey flostz-limestone, which is scarcely 

 translucent on the edges, and is full of petrifactions. 

 It has some resemblance to the limestone of the trans- 

 sition period, but only a very remote one to that of the 

 primitive. How great is the difference between the 

 granular translucent primitive limestone, and the dull 

 earthy and nearly opaque flcetz-'imestone ; and yet both 

 are members of a series of chemical formations, which 

 are still not the most distant. Chalk is a still newer for- 

 mation, and the limestone and marls of the Paris forma- 

 tion connect the foregoing members, which have been 

 deposited from the ocean, with the calc-tuff, the lowest 

 link of this series of formations (if we do not include the 

 coral-rocks that are daily forming) which has been 

 formed on the land. . We have thus a complete series 

 from the earliest to the latest period, in which we ob- 

 serve a gradual disappearance of the crystalline, and 

 increase of the earthy aspect, corresponding with the 

 relative age of the different members of the series, and 

 the state of the solvent from which they were precipi- 

 tated, and all serving as proofs of the immensely great, 

 but gradual alteration, of the state of the universal waters. 

 If we even examine the individual members of this 

 series, we find these gradations still more minute, but 

 always very characteristic. Thus the limestone of the 

 primitive period, (that which occurs in gneiss,) has the 

 largest granular distinct concretions, and possesses the 

 highest degree of translucidity and lustre, and has 

 therefore the most highly crystalline structure of the 

 whole series. Does not the highly crystalline structure 

 correspond most intimately with a calm state of the so- 

 lution ? The next member of the series, which is still 

 crystalline, but with smaller distinct concretions, oc- 

 curs in mica-slate; and, still less crystalline, or with 

 smaller distinct concretions, in the oldest clay-slate. In 

 the newer clay-slate, on the contrary, the distinct con- 

 cretions are so small, as only to be discoverable by their 

 glimmering and translucidity. The white colour which 

 hitherto characterised the older limestone, is now inter. 

 mixed with black, red, &c. ; and the newest members 

 of this formation, form the transition to the products of 

 the next period. In the transition period, the limestone 

 is compact, translucent, glimmering, and variegated or 

 marbled 



The secondary or floetz limestone contains several for- 

 mations that resemble each other very much, and differ 

 principally by the newer being more earthy than the 

 older. To these succeed, as we have already mentioned, 

 chalk and calc-tuff, which are in general still more earthy 

 in their external appearance. 



It is not enough, Werner continues, to detail the dif- 

 ferences and agreements of this great series ; we must 

 also endeavour to discover how these have been pro- 

 duced. The whole series, as has been already observ- 

 ed, is completely chemical, yet the different member! 



