In summary: Big brains are energetically expensive.
The mother must take in lots of energy not only during pregnancy, but for a significant time after.
Many rocks and organisms contain radioactive isotopes, such as U-235 and C-14.
These radioactive isotopes are unstable, decaying over time at a predictable rate.
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 (see lowest purple and green shading in diagram).
As the isotopes decay, they give off particles from their nucleus and become a different isotope.
The parent isotope is the original unstable isotope, and daughter isotopes are the stable product of the decay. In the first 5,730 years, the organism will lose half of its C-14 isotopes.
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.