(Geological
Transactions 1st Series volume 4 page 413.)
VITREOUS SPONGES OF THE CHALK.
These pear-shaped masses of flint often resemble in shape and size the large
sponges called Neptune's Cups (Spongia patera, Hardw.), which grow in the seas
of Sumatra; and if we could suppose a series of such gigantic sponges to be
separated from each other, like trees in a forest, and the individuals of each
successive generation to grow on the exact spot where the parent sponge died and
was enveloped in calcareous mud, so that they should become piled one above the
other in a vertical column, their growth keeping pace with the accumulation of
the enveloping calcareous mud, a counterpart of the phenomena of the Horstead
pot-stones might be obtained.
(FIGURE 238. Ventriculites radiatus, Mantell. Syn. Ocellaria radiata. D'Orbigny.
White chalk.)
Professor Wyville Thomson, describing the modern soundings in 1869 off the north
coast of Scotland, speaks of the ooze or chalk mud brought from a depth of about
3000 feet, and states that at one haul they obtained forty specimens of vitreous
sponges buried in the mud.
Pages:
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553