Deep inside the Inner Gorge of Grand Canyon, northern Arizona, are the crystalline basement rocks that probably date back even to the Creation Week itself. Clearly visible in the canyon walls are the light-colored granites, such as the Zoroaster Granite, which are stark against the darker, folded strata of the Vishnu Schist and the other metamorphic rock units of the Granite Gorge Metamorphic Suite 1 see lowest purple and green shading in diagram. These are former sedimentary and volcanic strata that have been transformed by heat and pressure, possibly during the intense upheavals when the dry land was formed on Day 3 of Creation Week. These were originally basalt lava flows several meters to tens of meters thick. In some outcrops pillow structures have been preserved, testimony to the basalt lavas having originally erupted and flowed under water onto the Creation Week ocean floor.
Home earth Earth History Geologist Radioactive. Read about How do we know the Age of the Earth? Radiometric dating using the naturally-occurring radioactive elements is simple in concept even though technically complex. If we know the number of radioactive parent atoms present when a rock formed and the number present now, we can calculate the age of the rock using the decay constant. The number of parent atoms originally present is simply the number present now plus the number of daughter atoms formed by the decay, both of which are quantities that can be measured.
As someone who has studied radioactivity in detail, I have always been a bit amused by the assertion that radioactive dating is a precise way to determine the age of an object. This false notion is often promoted when radioactive dates are listed with utterly unrealistic error bars. In this report , for example, we are told that using one radioactive dating technique, a lunar rock sample is 4, million years old, plus or minus 23 million years old. Of course, that error estimate is complete nonsense. It refers to one specific source of error — the uncertainty in the measurement of the amounts of various atoms used in the analysis.
Go to the: 30 Second Video Menu. Tools for measuring things must be calibrated against a known standard. When rocks from Mt.