internal Structure of the Magnesian Limestone. \9\ 



Conclusion. 



1. Considering the new red sandstone series as one great complex forma- 

 tion, we are enabled, after the details given in the two preceding chapters, to 

 separate it into the following natural divisions. 1. Lower red sandstone. 

 2. Marl-slate and compact limestone; or 2a. Compact and shelly limestone, 

 and variegated marls. 3. Yellow magnesian limestone. 4. Lower red marl 

 and gypsum. 5. Upper thin-bedded limestone. 6. Upper red sandstone. 

 7. Upper red marl and gypsum. 



In the whole range of this great system of deposits, through an extent of 

 nearly two hundred miles, these divisions, wherever they occur, are in a con- 

 stant order: but there are very few transverse sections of the country where 

 the whole of them are exhibited together. 



It further appears from the details of the previous chapter, that No. i. is 

 the equivalent of the rothe-todte-liegende ; No. 2. of the kupfcr-schiefcr and 

 zechstein; and that Nos. 3. 4. and 5. are the equivalents of the rauchwacke, 

 gypsum, asche, stinkstein, &c. &c. of the Thuringerwald. In the same part 

 of Germany, the deposits immediately superior to those last enumerated are, 

 hunter sandstein, muschelkalkstein, keuper (composed of vai'iegated marls, 

 (marnes irisees), sandstone, rock-salt, &c.), and lias. Nos. 6. and 7. are, 

 therefore, both in position and mineralogical character, the exact represen- 

 tatives of the hunter sandstein and keuper; the muschelkalk not having yet 

 been discovered in our geological series*. Such a coincidence in the sub- 

 divisions of two distant mechanical deposits, even on the supposition of their 

 being strictly contemporaneous, is truly astonishing. It has not been assumed 

 hypothetically, but is the fair result of the facts which are recorded in this 

 paper. 



2. The previous statements seem to show, that the system of the new red 

 sandstone could not have been produced by any sudden and transitory agency, 

 but must have been the result of causes of very extensive operation, and long 

 continuance; a conclusion which is confirmed by the peculiar groups of 

 organic remains v/hich exist in certain portions of the deposit. 



3. Notwithstanding the entire break which, in many parts of England, exists 



* English geologists in their first attempts to compare our secondary formations with (liose of 

 the continent, identified the tnuschelkalk with the lias: but (lie opinion has been since generally 

 abandoned. Continental geologists have also been at issue on the nature of the deposit inime- 

 diately superior to the muschelkalk. Since the publication of many excellent details connected 

 with this subject by MM. Oycnhaiissen and Dechen, confirmed as they have been by the subse- 

 quent observations of MM. de Beaumont and Dnfrenoy in various parts of France, the question 

 now appears to bo nearly set at rest, and the succession of the lower secondary formations to be 

 established in the order stated in the text. 



VOL. III. SECOND SERIES. R 



