<Tr> <Td> U </Td> <Td> 9.46 × 10 </Td> <Td> 4.47 × 10 </Td> <Td> 30.8 × 10 </Td> <Td> 2.91 × 10 </Td> </Tr> <Tr> <Td> U </Td> <Td> 5.69 × 10 </Td> <Td> 7.04 × 10 </Td> <Td> 0.22 × 10 </Td> <Td> 1.25 × 10 </Td> </Tr> <Tr> <Td> Th </Td> <Td> 2.64 × 10 </Td> <Td> 1.40 × 10 </Td> <Td> 124 × 10 </Td> <Td> 3.27 × 10 </Td> </Tr> <Tr> <Td> </Td> <Td> 2.92 × 10 </Td> <Td> 1.25 × 10 </Td> <Td> 36.9 × 10 </Td> <Td> 1.08 × 10 </Td> </Tr>

The geothermal gradient is the rate at which pressure increases below earth's surface