Yet lava flows that have occurred in the present have been tested soon after they erupted, and they invariably contained much more argon-40 than expected.1 For example, when a sample of the lava in the Mt. Helens crater (that had been observed to form and cool in 1986) ( age yield incorrect old potassium-argon ages due to the extra argon-40 that they inherited from the erupting volcanoes, then ancient lava flows of unknown ages could likewise have inherited extra argon-40 and yield excessively old ages.There are similar problems with the other radioactive “clocks.” For example, consider the dating of Grand Canyon’s basalts (rocks formed by lava cooling at the earth’s surface).Based on these observations and the known rate of radioactive decay, they estimate the time it has taken for the daughter isotope to accumulate in the rock.
Nevertheless, geologists insist the radioactive decay rates have always been constant, because it makes these radioactive clocks “work”!
New evidence, however, has recently been discovered that can only be explained by the radioactive decay rates not having been constant in the past.9 For example, the radioactive decay of uranium in tiny crystals in a New Mexico granite ( yields a uranium-lead “age” of 1.5 billion years.
Yet this view is based on a misunderstanding of how radiometric dating works.
Part 1 (in the previous issue) explained how scientists observe unstable atoms changing into stable atoms in the present.
PART 1: Back to Basics PART 2: Problems with the Assumptions PART 3: Making Sense of the Patterns This three-part series will help you properly understand radiometric dating, the assumptions that lead to inaccurate dates, and the clues about what really happened in the past.