1. gastroliths - stones swallowed by dinosaurs and by modern birds to help with digestion.
2. photovoltaic cell - device made of silicon that turns sunlight directly into electric current.
3. uniformitarianism - states that Earth processess happening today are similar to those that happened in the past.
4. tephra - bits of rock or solidified lava dropped from the air during an explosive volcanic eruption.
5. mascon - concentration of mass on the moon located beneath an impact basin.
