by rstevenson » Fri Jun 04, 2010 3:14 pm
dougettinger wrote:... Why is there a tremendous gap in the ages of rocks found on Earth? ...
I don''t see that big a gap. I've personally walked on rocks approximately 1 B years old, as well as others in the range of 2.7 B years old -- both in and around the Canadian Shield -- as well as that first one I mentioned, the 3.5 B year old bit. Within an hours drive of home I can put my hands on sandstone about 275 M years old, and then drive another hour to reach a Unesco World Heritage site where fossils are being found in rock about 320 M years old. In short, there's a wide range of ages of rocks all around us.
dougettinger wrote:The oldest super-continent is determined to be about 750 million old before it drifted apart and then recombined to form the next supercontinent. What happen to this continent(s) between the ages to 2.5 billion years and 750 million years ? Did the first supercontinent which I believe resided mostly in the southern polar regions stay in this dormant position all those years ?
I think you're referring to Rodinia. That's only one of many super-continents that have formed and broken up during the course of the Earth's life, and it's definitely not the oldest. Wikipedia has
a page listing them all and linking to more info about each.
Rob
[quote="dougettinger"]... Why is there a tremendous gap in the ages of rocks found on Earth? ...[/quote]
I don''t see that big a gap. I've personally walked on rocks approximately 1 B years old, as well as others in the range of 2.7 B years old -- both in and around the Canadian Shield -- as well as that first one I mentioned, the 3.5 B year old bit. Within an hours drive of home I can put my hands on sandstone about 275 M years old, and then drive another hour to reach a Unesco World Heritage site where fossils are being found in rock about 320 M years old. In short, there's a wide range of ages of rocks all around us.
[quote="dougettinger"]The oldest super-continent is determined to be about 750 million old before it drifted apart and then recombined to form the next supercontinent. What happen to this continent(s) between the ages to 2.5 billion years and 750 million years ? Did the first supercontinent which I believe resided mostly in the southern polar regions stay in this dormant position all those years ?[/quote]
I think you're referring to Rodinia. That's only one of many super-continents that have formed and broken up during the course of the Earth's life, and it's definitely not the oldest. Wikipedia has [url=http://en.wikipedia.org/wiki/List_of_supercontinents]a page[/url] listing them all and linking to more info about each.
Rob