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"jack malda" Discussed on The Science Show
"And one observation you could make from up there in the sky is that the coastline of northern Tasmania is nowhere near resign. Arizona. A-? You could also just look at the map, of course. So how come it seems like they were once joined here. Sancho producer, David Fisher to geologists the rocks along Tasmania's northern coast don't feet they stick out as different from adjacent formations. So where did they come from? How did they get there? And are they related to formations elsewhere in the world? After much searching, the rocks of the US south west with thought to be a possible match and a good place to look and American geologists had a similar mystery to solve anxious formations in the southwest seemed to be sheared off do they extend onto some other continent. So Jack Malda went deep down into the Grand Canyon where anxious rocks are exposed and where stories of our planet's history. Come to light, the first striking thing to me is when we got down to Grand Canyon. He could sit on these rocks. And I would just a dead ring of what we were looking at intense, minus physically the rocks. Look the same. And then when we started doing some chemical analysis, and is dieting that all lined up as well and dislikes very similar on over audio Scouse the age of these rocks is revealed by studying the mineral zircon the rocks. We're talking about here. I ancient sedimentary rocks. That will once lies of sand. Deposited in a shallow election, and some of those grinds these mineral codes, Akon seconds. A really interesting very useful in because we can diet till old that grinds minutes because they are con- contains tiny little amounts of uranium in there, which decays to lead. First thing we do when we get these samples is we essentially crush them up and separate Elise. Tiny little silicon grains out of them. And then once we have those cons. We analyze them on our mass spectrometer, it's linked up to Elisa. So essentially blast these tiny loser on grinds. We can measure the different price shares of uranium and lead coming out of this kind to tell old there's a concert, and how old are they the youngest their consumer finding or about one point one billion years old, and there's a spirit of ages. Although I to about three billion years old. So there's a lot of history preserved in those tiny loser owns the dating process pinpoints a specific time when a crystalline mineral. Who was trapped in its surrounding rock each sample contains a specific quantity of crystals from specific dates together. They form a unique signature if the signatures of two samples match chances are they were produced from the same source. These cons growing in things like Granitz that were originally magmatic rocks when they can start to crystallize at of the magma fell cooldown enough that the lead that's decaying out of the Ryan, we'll get trapped in the mineral and from that point onwards that laid we'll continue to accumulate within as a crystal. And then when we measure the amount of light in there, we can figure out how long that grind must have been sitting there accumulating lead because we know half us uranium decay. Split why could your sample in Tasmania not have come from somewhere else? How can you be sure that it has a good question? That's something we spent quite a bit of time thinking about and essentially it comes back again in a large part to these cones. So these coincidentally rocks coming from older rocks so old mountain belts. Eroding. Eroding. The sand and motto of which eventually gets transported, Dan and rivers and deposited in these sedimentary basins when you look at the range of ages of cones owns within your city Metri rock he can use that as a fingerprint of the oldest source rocks that they sediments came from. So when we did this with TEZ Manion rocks. We compare those ages to nibble at rooks in Astrada, so older rocks in a strategy that could have potentially been the source for the Tasmanian sentiments what you say when you do that is that those two signatures. Don't overlap so desert kinds in the Tasmanian rocks and not coming from anyway in astrology. That's at least exposed at the present. I could not be linked to south. Some buried depositing Europe. How can you be sure that the Grand Canyon deposit was related to your Tasmanian deposit? Look, it's a great question and looking at very action rocks like the ones where by looking at..