. Relics of primeval life, beginning of life in the dawn of geological time. relations to the containing rocksand minerals being admitted, no rational explana-tion of its origin seems at present possible otherthan that advocated in the preceding pages. If the reader will now turn to the figures in theillustration on the opposite page (Fig. 59), he willfind a selection of examples bearing on the abovearguments and objections. Fig. i represents a por-tion of a very thin slice of a specimen traversed byveins of fibrous serpentine or chrysotile, and havingthe calcite of the walls more broken by cl
. Relics of primeval life, beginning of life in the dawn of geological time. relations to the containing rocksand minerals being admitted, no rational explana-tion of its origin seems at present possible otherthan that advocated in the preceding pages. If the reader will now turn to the figures in theillustration on the opposite page (Fig. 59), he willfind a selection of examples bearing on the abovearguments and objections. Fig. i represents a por-tion of a very thin slice of a specimen traversed byveins of fibrous serpentine or chrysotile, and havingthe calcite of the walls more broken by cleavageplanes than usual. The portion selected shows a partof one of the chambers filled with serpentine, whichpresents the usual curdled aspect almost impossibleto represent in a drawing (s). It is traversed by abranching vein of chrysotile (s), which, where cutprecisely parallel to its fibres, shows clear fine crosslines, indicating the sides of its constituent prisms,and where the plane of section has passed obliquelyto its fibres, has a curiously stippled or frowsy ap-. X 60 Fig. 59.—Figures of vaiious Structures and States of Preservation. Fig. I.—Portion of two laminae and intervening serpentine, with chrj-sotile vein. {a) Proper wall tubulated. (b) Intermediate skeleton, with large canals. (fii Openings of small chamberlets filled with serpentine. {s) Serpentine filling chamber. (j>) Vein of chrysotile, showing its difference from the proper 2.—Junction of a canal and the proper wall. Lettering as in Fig. 3.—Proper wall shifted by a fault, and more recent chrysotile vein not faulted. Lettering as in Fig. 4.—Large and small canals filled with 5.—Abnormally thick portion of intermediate skeleton, with large tubes and small canals filled with dolomite. 237 DIFFICULTIES AND OBJECTIONS 239 pearance. On either side of the serpentine band isthe nummuline or proper wall, showing under a lowpower a milky appearance, which, with
Size: 1233px × 2027px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthordawsonjohnwilliamsir1, bookcentury1800, bookdecade1890
