 The oldest rocks on Earth came in three categories, one, the rocks that formed here when the magma from the Great Impact solidified, two, the rocks we brought here from the Moon, and three, the rocks that landed here as meteorites. We'll focus on the first two. The Jack Hills are a range of hills in Midwest Western Australia, about 800 kilometers as 500 miles north of Perth. Zircons were found in sedimentary rock, indicating that they were sourced from pre-existing rocks which were then eroded by the weather. In January 2001, Nature published an article on Curtin University's study of these Jack Hills zircon crystals. Using uranium-led zircon analysis, following standard operating techniques like the ones we just covered, they found the oldest solid-Earth crust matter ever discovered at 4.356 billion years old. At the end of the 1st Apollo 14 EVA, a large soil sample was collected from the area near the lander. The bulk of the soil sample was scooped from a small crater. The Apollo 14163 was chosen as one of the reference soils for the Lunar Highlands suite. Scientists used a chemical abrasion isotope dilution thermal ionization mass spectrometry analysis on zircon crystals in the sample, like the process we used for our Earthrock sample. The oldest crystal, identified as Z59, was found to be 4.3 billion years old. This is quite close to the oldest Earthrock, indicating that they formed at the same time. We previously established via oxygen isotope ratios that they formed at the same place. These two findings constitute significant support for the giant impact hypothesis, but the giant impact idea remains a hypothesis. Dating methods are evolving. Different dating methods indicate different ages for moon rocks. The search for rocks on Earth continues. Another trip to the moon could change our view completely. But for now, in early 2020, the general scientific consensus is that the current version of the Earth is at least 4.3 billion years old, and the moon is close to the same age. This is interesting, but it does not tell us how long ago the earlier version of the Earth was formed. For that, we need to date rocks that formed beyond the Earth, rocks that never went through the melt and re-hardening process, like all the rocks on the Earth and the moon. For this, we need to examine meteorites.