1 00:00:01,840 --> 00:00:07,840 Speaker 1: Welcome to Brainstuff, a production of iHeartRadio. Hey Brainstuff, Lauren 2 00:00:07,880 --> 00:00:11,719 Speaker 1: vogelbomb here with a classic episode from our podcast's archives. 3 00:00:12,720 --> 00:00:16,000 Speaker 1: The substance of the Earth's crust is changing all the time, 4 00:00:16,320 --> 00:00:19,439 Speaker 1: though not usually on a timescale that we really observe. 5 00:00:20,120 --> 00:00:23,480 Speaker 1: You know, Rivers and lakes and even oceans carve out 6 00:00:23,640 --> 00:00:29,040 Speaker 1: territory and then recede. Mountains rise and fall, all impacting 7 00:00:29,120 --> 00:00:33,479 Speaker 1: the makeup of Earth's surface in traceable ways. Back in 8 00:00:33,520 --> 00:00:37,680 Speaker 1: twenty nineteen, researchers announced that they discovered what's likely the 9 00:00:37,720 --> 00:00:41,760 Speaker 1: oldest surviving bit of rock ever found, and they found 10 00:00:41,760 --> 00:00:46,440 Speaker 1: it in a piece of moon rock. Hey brain Stuff, 11 00:00:46,479 --> 00:00:50,920 Speaker 1: laurenvoglebomb here. On February sixth, nineteen seventy one, the late 12 00:00:51,000 --> 00:00:54,520 Speaker 1: astronaut Alan Shepherd, the commander of NASA's Apollo fourteen mission, 13 00:00:54,760 --> 00:00:58,040 Speaker 1: was taking a walk on the Moon. He and fellow 14 00:00:58,080 --> 00:01:01,040 Speaker 1: space traveler Edgar Mitchell were out gathering rocks around a 15 00:01:01,080 --> 00:01:04,920 Speaker 1: depression called Cone Crater. To quote Sheppard himself, Many of 16 00:01:04,959 --> 00:01:08,119 Speaker 1: these were hand sized grab samples, but the pair took 17 00:01:08,200 --> 00:01:12,959 Speaker 1: home some larger mementos too. One basketball sized rock collected 18 00:01:12,959 --> 00:01:17,440 Speaker 1: by Shepherd earned itself a nickname Big Bertha, officially known 19 00:01:17,480 --> 00:01:20,760 Speaker 1: as Lunar Sample one four three two one. Big Bertha 20 00:01:20,800 --> 00:01:23,880 Speaker 1: weighs about nineteen pounds that's nine kilograms, making it the 21 00:01:24,000 --> 00:01:26,679 Speaker 1: largest rock that Apollo fourteen brought back to Earth and 22 00:01:26,720 --> 00:01:29,720 Speaker 1: the third largest collected by any of the Apollo missions. 23 00:01:30,480 --> 00:01:33,440 Speaker 1: Although Shepherd found Big Bertha on the Moon, that may 24 00:01:33,480 --> 00:01:37,080 Speaker 1: not be where its story began. The rock is a breccia, 25 00:01:37,319 --> 00:01:40,640 Speaker 1: a hodgepodge of geologic fragments called clasts, which are held 26 00:01:40,640 --> 00:01:44,240 Speaker 1: together by a cement like mix. A newly published hypothesis 27 00:01:44,280 --> 00:01:46,959 Speaker 1: says that part of Big Bertha formed billions of years 28 00:01:46,959 --> 00:01:50,800 Speaker 1: ago right here on planet Earth. In fact, despite the 29 00:01:50,880 --> 00:01:55,040 Speaker 1: lunar connection, this could represent the oldest Earth rock ever discovered. 30 00:01:56,160 --> 00:01:58,440 Speaker 1: Big Bertha's origins were the focus of a study that 31 00:01:58,480 --> 00:02:01,200 Speaker 1: was published in January in the journal Earth and Planetary 32 00:02:01,200 --> 00:02:04,880 Speaker 1: Science Letters. The paper's authors include an international team of 33 00:02:04,920 --> 00:02:08,400 Speaker 1: geoscientists who looked the Moon rocks procured by Apollo fourteen, 34 00:02:08,680 --> 00:02:12,080 Speaker 1: including Lunar Sample one four three two one. For the 35 00:02:12,120 --> 00:02:15,400 Speaker 1: most part, the clasts on this famous breccia are dark gray, 36 00:02:15,680 --> 00:02:18,560 Speaker 1: but there's also a lightly colored one that catches the eye. 37 00:02:19,080 --> 00:02:21,560 Speaker 1: It's made of fill sight a kind of volcanic rock 38 00:02:21,600 --> 00:02:25,560 Speaker 1: that contains the minerals feldspar, and quartz. The light gray class, 39 00:02:25,680 --> 00:02:28,680 Speaker 1: which is two centimeters that's point seven inches across, is 40 00:02:28,800 --> 00:02:32,960 Speaker 1: loaded with tiny zircon crystals as well. Many zircons contain 41 00:02:33,080 --> 00:02:35,760 Speaker 1: vital information about what the environment was like, when and 42 00:02:35,800 --> 00:02:39,600 Speaker 1: where they formed. Close inspection of the zircons in Big 43 00:02:39,639 --> 00:02:42,480 Speaker 1: Bertha's light patch showed that the crystals were produced by cool, 44 00:02:42,560 --> 00:02:46,240 Speaker 1: oxygen rich magma. Yet molten rock of this sort doesn't 45 00:02:46,280 --> 00:02:49,560 Speaker 1: exist anywhere near the Moon's surface. To find some, you'd 46 00:02:49,600 --> 00:02:51,560 Speaker 1: need to travel more than one hundred miles that's one 47 00:02:51,639 --> 00:02:54,360 Speaker 1: hundred and sixty two kilometers below the surface of the 48 00:02:54,360 --> 00:02:58,240 Speaker 1: Moon where Shepherd and Mitchell found Big Bertha. So how 49 00:02:58,240 --> 00:03:01,359 Speaker 1: did these zircons and the class they belong to end 50 00:03:01,440 --> 00:03:04,959 Speaker 1: up on the surface. A violent impact was probably involved. 51 00:03:05,320 --> 00:03:08,400 Speaker 1: When a meteorite or asteroid smacks into a planet or moon, 52 00:03:08,680 --> 00:03:11,359 Speaker 1: it can transport material that's buried deep under the crust 53 00:03:11,480 --> 00:03:15,120 Speaker 1: up to the surface. And as noted earlier, Big Bertha 54 00:03:15,280 --> 00:03:19,680 Speaker 1: was found near an impact crater, So case closed, right, Well, 55 00:03:20,000 --> 00:03:23,880 Speaker 1: maybe not Cone crater, an expanse measuring about two hundred 56 00:03:23,880 --> 00:03:26,080 Speaker 1: and fifty feet to that seventy six meters deep and 57 00:03:26,120 --> 00:03:28,600 Speaker 1: one thousand feet or three hundred and four meters wide 58 00:03:29,000 --> 00:03:32,639 Speaker 1: was created roughly twenty six million years ago. Scientists think 59 00:03:32,639 --> 00:03:35,160 Speaker 1: that the violent episode that left this depression behind would 60 00:03:35,160 --> 00:03:37,720 Speaker 1: have failed to dredge up any geologic material lying more 61 00:03:37,760 --> 00:03:41,160 Speaker 1: than forty five miles or seventy two kilometers underneath the Moon. 62 00:03:42,200 --> 00:03:44,800 Speaker 1: A Big Berth Is Fell site classed could have originated 63 00:03:44,840 --> 00:03:48,480 Speaker 1: deep in a lunar magma pocket, but it doesn't seem likely. 64 00:03:48,960 --> 00:03:52,520 Speaker 1: The study authors think a different scenario is way more plausible. 65 00:03:53,800 --> 00:03:57,360 Speaker 1: Around twelve miles or nineteen kilometers below Planet Earth's surface, 66 00:03:57,600 --> 00:04:01,360 Speaker 1: there's a supply of cool oxidized magma. This is exactly 67 00:04:01,360 --> 00:04:03,800 Speaker 1: the kind of raw material that probably made the zircons 68 00:04:03,800 --> 00:04:06,640 Speaker 1: on Big Berth as light patch. And by the way, 69 00:04:06,920 --> 00:04:11,120 Speaker 1: zircon crystals have a helpful habit of preserving uranium isotopes. 70 00:04:11,520 --> 00:04:14,760 Speaker 1: Those can be used for radiometric dating, a process that 71 00:04:14,800 --> 00:04:17,479 Speaker 1: tells us the Fell site clast is four point oh 72 00:04:17,720 --> 00:04:21,840 Speaker 1: to four point one billion years old. Put both of 73 00:04:21,880 --> 00:04:25,120 Speaker 1: these clues together and a potential timeline of events emerges. 74 00:04:25,560 --> 00:04:28,640 Speaker 1: According to the hypothesis championed in the study. Some of 75 00:04:28,640 --> 00:04:32,440 Speaker 1: that cool oxidized magma lying deep under Earth's continental crust 76 00:04:32,680 --> 00:04:35,200 Speaker 1: hardened into this clast between four point oh and four 77 00:04:35,279 --> 00:04:38,280 Speaker 1: point one billion years ago. We know that our planet 78 00:04:38,320 --> 00:04:41,120 Speaker 1: was besieged by meteorites in those days, a process that 79 00:04:41,160 --> 00:04:44,600 Speaker 1: by the way, created a lot of old granites. Repeat 80 00:04:44,640 --> 00:04:47,320 Speaker 1: impacts would have driven the class ever closer to the surface, 81 00:04:47,600 --> 00:04:50,719 Speaker 1: until finally a projectile hit the Earth with enough force 82 00:04:50,880 --> 00:04:54,560 Speaker 1: to launch the fell site clear out into space. It's 83 00:04:54,720 --> 00:04:57,640 Speaker 1: estimated that four billion years ago our Moon was around 84 00:04:57,640 --> 00:05:00,200 Speaker 1: three times closer to Earth than it is right now. 85 00:05:00,720 --> 00:05:03,360 Speaker 1: The far flung clast might have bridged the gap and 86 00:05:03,400 --> 00:05:07,479 Speaker 1: settled on the Moon, but around that time meteorites from 87 00:05:07,480 --> 00:05:11,279 Speaker 1: space also harassed the Moon, and approximately three point nine 88 00:05:11,279 --> 00:05:14,280 Speaker 1: billion years ago, one of these impacts could have partially 89 00:05:14,320 --> 00:05:17,000 Speaker 1: melted the class and driven it under a lunar surface, 90 00:05:17,000 --> 00:05:21,520 Speaker 1: where it merged with other clasts and became part of Abreccia. Then, 91 00:05:21,800 --> 00:05:24,600 Speaker 1: twenty six million years ago, the asteroid strike that gave 92 00:05:24,640 --> 00:05:26,960 Speaker 1: birth to the Cone Crater could have set Big Berth 93 00:05:27,000 --> 00:05:29,480 Speaker 1: a free, propelling it to the spot where Alan Shepherd 94 00:05:29,560 --> 00:05:31,920 Speaker 1: came and grabbed it up one historic day in nineteen 95 00:05:31,960 --> 00:05:35,360 Speaker 1: seventy one. If the felsite class really did have a 96 00:05:35,480 --> 00:05:39,000 Speaker 1: terrestrial origin, then, ironically enough, it might be the oldest 97 00:05:39,040 --> 00:05:42,400 Speaker 1: known rock from planet Earth. There's a four point zero 98 00:05:42,520 --> 00:05:46,200 Speaker 1: three billion year old rock from Canada's Northwest Territories that's 99 00:05:46,279 --> 00:05:49,359 Speaker 1: comparable in age and over in Quebec, the Greenstone Belt 100 00:05:49,360 --> 00:05:52,400 Speaker 1: is at least three point nine billion years old. Out 101 00:05:52,400 --> 00:05:55,279 Speaker 1: in the jack Hills of Western Australia, scientists have located 102 00:05:55,360 --> 00:05:58,799 Speaker 1: zircons that formed roughly four point three seven billion years ago, 103 00:05:59,200 --> 00:06:01,720 Speaker 1: but these crystals sely detached from their original rocks at 104 00:06:01,760 --> 00:06:04,800 Speaker 1: some point. Big Birth is felsite class and at zircons 105 00:06:04,839 --> 00:06:14,760 Speaker 1: seem to have formed simultaneously. Today's episode is based on 106 00:06:14,800 --> 00:06:17,520 Speaker 1: the article Earth's oldest rock may have been discovered on 107 00:06:17,640 --> 00:06:20,560 Speaker 1: the Moon on HowStuffWorks dot com, written by Mark Mancini. 108 00:06:21,040 --> 00:06:23,599 Speaker 1: Brain Stuff is production of iHeartRadio in partnership with how 109 00:06:23,600 --> 00:06:25,920 Speaker 1: Stuffworks dot Com, and it is produced by Tyler Klang. 110 00:06:26,400 --> 00:06:29,560 Speaker 1: Four more podcasts my heart Radio, visit the iHeartRadio app, 111 00:06:29,720 --> 00:06:32,640 Speaker 1: Apple Podcasts, or wherever you listen to your favorite shows.