. Fossil plants : for students of botany and geology . Paleobotany. IV] FOSSIL WOOD. 61 have a piece of coniferous wood with the shell of an Ammonite (Aegoceras planicosta Sow.) lying on it; the specimen was found in the Lower Lias clay at Lyme Regis, and illustrates the accidental association of a drifted piece of a forest tree with a. Pig. 7. Aegoceras planicosta Sow. on a piece of coniferous wood, Lower Lias, Lyme Begis, Prom a specimen in the British Museum. Slightly reduced. shell which marks at once the age and the marine character of the beds. Again in fig. 8 we have a block of flint pa
. Fossil plants : for students of botany and geology . Paleobotany. IV] FOSSIL WOOD. 61 have a piece of coniferous wood with the shell of an Ammonite (Aegoceras planicosta Sow.) lying on it; the specimen was found in the Lower Lias clay at Lyme Regis, and illustrates the accidental association of a drifted piece of a forest tree with a. Pig. 7. Aegoceras planicosta Sow. on a piece of coniferous wood, Lower Lias, Lyme Begis, Prom a specimen in the British Museum. Slightly reduced. shell which marks at once the age and the marine character of the beds. Again in fig. 8 we have a block of flint partially en- closing a piece of coniferous wood in which the internal structure has been clearly preserved in silica. This specimen was found in the chalk, a deposit laid down in the clear and deep water of the Cretaceous sea. The wood must have floated for some time before it became water-logged and sank to the sea-floor. In the light coloured wood there occur here and there dark spots which mark the position of siliceous plugs b, b filling up clean cut holes bored by Teredos in the woody tissue. The wood became at last enclosed by siliceous sediment and its tissues penetrated by silica in solution, which gradually replaced and preserved in wonderful perfection the form of the original. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Seward, A. C. (Albert Charles), 1863-1941. Cambridge : University Press
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishercambr, bookyear1898
