Books about Agate Jan 30, 2023 3:18:23 GMT -5 RWA3006, gemfeller, and 6 more like this
Post by 1dave on Jan 30, 2023 3:18:23 GMT -5
Roger K. Pabian is an interesting person, in 2005 he wrote:
“Biologic crises and mass extinctions---The Lake Superior agate that formed in place in volcanic rocks of late Precambrian age are an example of an abundant, widespread occurrence of agates that takes place at about the same time in the earth’s history that there is a considerable change in faunas.
During this time, the primitive Ediacaran faunas are giving way to the shelly faunas of the early Cambrian. During the Devonian, the abundant agate resources of Scotland formed at about the same time faunas changed from early to late Paleozoic constituencies. The colonial animals, primitive mollusks and trilobites gave way to echinoderm rich fauna, goniatite mollusks, and many trilobite families perished.
Many of the world’s largest agate occurrences are found the Permian-Triassic boundary, the greatest mass extinction of all time. Many of the agates of Brazil, Germany, Poland, Australia, and South Africa all are products of this time.
Agate formation continued on into the Triassic as evidenced by extensive deposits along the eastern seaboard of the US, starting in about North Carolina, and extending northeastward into New Brunswick and Nova Scotia in Canada.
The extensive agate deposits of India are related to the Deccan basalts of late Cretaceous age (Bose, 1908-1909, Officer and Drake, 1985), flows that some researchers think were caused by the late Cretaceous impact that brought about the demise of dinosaurs, ammonites, and hundreds of species of foraminifers.
Abundant agate deposits in the Miocene of Texas and or Oregon came about at about the same time as important changes in both terrestrial and marine faunas.” - Roger K. Pabian