SKELETONS: the frame of life by JAN ZALASIEWICZ & MARK WILLIAMS

Author:JAN ZALASIEWICZ & MARK WILLIAMS
Language: eng
Format: epub
Published: 2018-01-05T12:56:51+00:00

* * *

OUP CORRECTED PROOF – FINAL, 3/1/2018, SPi

-

(palaeontologists can help the process by dunking pieces of the rock in

acid, so that these perfect, chemically transformed fossils can be extracted

whole). The reef contains other, more practical, types of wealth too. Its

cavity-rich, porous nature means that while it was buried deep under-

ground it trapped fluids with hydrocarbons—some of which are still

present at depth beneath the basin—and also fluids rich in dissolved

metals, which converted it into a kind of underground Aladdin’s cave,

through filling some of those cavities with mineral ores of lead and zinc.

There are many uses of a dead reef, and much of their ‘academic’ study

has been carried out with a view to extracting the riches they contain.

The Canning reef is thought to have been a true, large-scale, robust

barrier reef. But these kinds of structures did not persist throughout the

Palaeozoic. The rise and fall of different groups of organisms through this

time meant that the possibilities of building a wave-resistant framework

fluctuated along with the fortunes of the main reef-builders. A major

mass extinction event in late Devonian, for instance, decimated many of

the main reef-builders of those times. During the succeeding Carbonifer-

ous Period, which is mostly known for its global spread of coal-forming

forests, true reefs were rare. Skeletons then piled up in different ways.

The Carboniferous is known as a time of carbonate ‘mounds’ and

‘buildups’. Like reefs, these are an accumulation of piles of skeletons of

corals, brachiopods, sponges, and other organisms. But these did not

generally form frameworks strong enough to resist the long-term pounding

of ocean waves. Rather, they built up as mounds, generally starting their

accumulation on sea floors that were below the reach of the waves. As

generation on generation of these organisms lived and died and left

their skeletons at the sea bed, the mound would build up towards sea

level, with the additional mass being added by mud trapped between the

skeletal debris, and by algae—seaweed—growing on them. As the mound

built up towards the sea surface, waves would then break up and redistribute

the debris.

This redistribution would make a difference to the Earth’s solid surface,

even on a planetary scale. Today, the coral reef structures, rimmed and



Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.