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CHAPTER XI. 



TABULAR ARRANGEMENT OF SECONDARY STRATA. RED SANDSTONE. 



MAGNESIAN LIMESTONE. ROCK SALT AND GYPSUM. 



Relative Geological Position of the Secondar}'- Class of Rocks. — Their Mineral 

 and Zoological Characters. — Tabular Arrangement. — New Red Sandstone and 

 Red Marl. — Upper, Middle, and Lower Beds, formed chiefly of the Fragments 

 of more ancient Rocks, broken by some great Convulsion. — Lowest Red Sand- 

 stone, or Rothe-todte-Liegende of the German Geologists. — Separated from the 

 Middle Beds, by Beds of Magnesian Limestone. — Middle and Upper Beds of 

 Red Sandstone and Marl; their Accordance with those of France and Ger- 

 many. — Muschel-Kalk wanting in England, but probably exists in Ireland, as 

 the Lily Encrinite has recently been discovered there. — Magnesian Limestone 

 of the Northern Counties. — English Red Marl and Sandstone formed of more 

 ancient Rocks, particularly of Porphyry and Trap. — Gypsum accompanying 

 Rock Salt originally Anhydrous. — Rock Salt Deposits, in different Formations. 



Secondary rock formations, comprise all the regular strata that 

 cover the transition rocks and coal measures, and terminate with 

 chalk. Their mineral characters may be briefly described, as they 

 occur in England, France, and part of Germany, They consist of 

 vast depositions of sandstone and conglomerate beds, and of numer- 

 ous calcareous beds, separated by beds of clay and sand. The lime- 

 stones are less crystalline, and more soft and earthy, than transition or 

 mountain limestone. They abound in remains of testaceous animals, 

 Vi^hich are chiefly marine shells ; but remains of fresh-water animals 

 occur in some of the secondary beds ; and parts of fossil terrestrial 

 vegetables are also sometimes found, proving the existence of dry 

 land, at the period when the strata were deposited. Secondary strata 

 cover a large portion of the habitable globe, and are the immediate 

 sub-soil of the most fertile districts in England, and of various parts 

 of Europe. No beds of good mineral coal are found in any part of 

 the secondary series of strata, above the regular coal measures in 

 England ; but some beds of imperfect coal, and wood coal, occur 

 in the secondary formations : and this is also the case in similar for- 

 mations on the Continent. Neither metallic veins nor metallic beds 

 deserving notice (except of iron ores) occur in this class of rocks ; 

 nor do they afford any of the rare species of crystallized minerals. 

 Rock-salt and gypsum are the most valuable minerals found in the 

 secondary strata ; and it is from them that all the important salt 

 springs issue. Some of the rocks in this class yield useful materials 

 for architecture ; but the stone is, generally, soft and perishable. 

 To the rocks of this class, Werner gave the name of floetz or flat 

 rocks, because, in the northern parts of Europe, they are generally 

 arranged in nearly horizontal strata ; but, this character is altogether 

 inapplicable to the upper secondary strata in the outer ranges of the 

 Alps, and in the Jura chain, where they may be observed, bent in 

 every possible direction, and sometimes nearly vertical. In these 



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