CAR 



[70] 



CAR 



it miich resembles India-rubber, 

 whence it has obtained its name. 



CA'BAPACE. The upper shell of 

 reptiles. 



CAEADOC SANDSTONE, The name given 

 to a formation constituting the 

 upper member of the Lower Silurian 

 Rocks. " The name has been 

 selected, says Sir R. Murchison, 

 because the strata of which it is 

 composed constitute a number of 

 eminences, which abut against the 

 remarkable chain of trap hills 

 called the Caradoc * Unlike the 

 sandstones of the upper Silurian 

 rocks, this formation is composed 

 essentially of sandstones of different 

 colours, with an occasional subor- 

 dinate course of calcareous matter. 

 The Caradoc sandstone formation 

 is made up of beds of red, green, 

 and purple sandstones, some of 

 which it is difficult, upon first 

 inspection, to distinguish from 

 strata of the old, or even the new 

 red sandstone. Its best and clear- 

 est distinctions consist in its order 

 of infra- position to the upper Silu- 

 rian rocks, and in its organic 

 remains, nearly all of which are 

 dissimilar from the fossils of the 

 formations which immediately over- 

 lie it. 



Among the fossils characteristic 

 of this formation may be enume- 

 ted Productus sericeus ; Bellero- 

 phon bilobatus and Bellerophon 

 acutus ; Littorina striatella ; Orthis 

 alternata ; Orthis collactis, and 

 Orthis canalis ; Pentamerus loavis 

 and Pentamerus oblongus. The 

 trilobites common to the upper 

 Silurian rocks are here wanting, 

 and instead are found other forms, 

 including the Trinucleus, a genus 

 not observed in the upper but 

 abounding in the lower Silurian 

 rocks : also a large species of 

 Asaphus, named by Sir R. Murchi- 

 son Asaphus Powisii. In other 

 beds of this formation there are 

 found Avicula orbicularis and 



Avicula obliqua ; Orthis actonia, 

 and Orthis grand is ; Orthis Ano- 

 mala ; Orthis vecten ; Orthis flabel- 

 lulum; and Orthis vespertilis; Tere- 

 bratula anomala, and Terebratula 

 anguis ; Pentamerus oblongus, and 

 the plumose coral Calamopora 

 fibrosa. 



Malachite, or the green carbon- 

 ate of copper, occurs in films and 

 nests. Thin strings of galena, 

 with some associated crystals of 

 blende, have been also found. For 

 a full description of this formation, 

 together with illustrations of the 

 contained fossils, the reader is 

 referred to SirR. Murchison's splen- 

 did work on the Silurian System, 

 from which the above is principally 

 extracted. 



CA'EBON. (ca/rbo, Lat. carlon, Sp. 

 carlone, It. charlon, Fr.) Caradoc 

 limestone. The pure inflammable 

 principle of charcoal. If a piece 

 of wood, or any vegetable matter, 

 be placed in a closed vessel, and 

 kept red-hot for some time, it is 

 converted into a shining black 

 brittle substance, possessing neither 

 smell nor taste, commonly known 

 as charcoal. Charcoal is infusible, 

 insoluble in water, is capable of 

 combining both with hydrogen and 

 sulphur, is a conductor of electri- 

 city, and has a powerful affinity 

 for oxygen. Carbon is obtained 

 nearly pure in charcoal ; but, what 

 is astonishing, the diamond appears 

 to be this elementary substance in 

 its purest known form. Why it 

 is, or how it is, that the same 

 elementary substance can, with 

 little or no addition, form two 

 bodies so dissimilar in every re- 

 spect as charcoal and diamond, the 

 one a soft, black, brittle mass, the 

 other the clearest and hardest body 

 we know of, is a mystery beyond 

 our weak comprehensions to under- 

 stand. Carbon enters as a consti- 

 tuent part into many of the slate 

 rocks, to which it generally com- 



