Limits to the former magnitude of the gravity force at the Earth’s surface, g, with respect to the present magnitude go, have been determined by five methods, i. The permanent existence of a terrestrial atmosphere over the last 37 x 109 years (0.33 go < g) 2. Dimensions of vertebrates: Jurassic Apatosaurus (g < 1.2 go) and Upper Cretaceous Pteranodon (g < 2 go) 3. Miocene overconsolidation of the London Clay (0.5 go< g < go) 4. Phanerozoic upper mantle mineralogy (0.4 go< g < 2.2 go) 5. Crustal mineralogy during the Phanerozoic (0.5 g0 < g< 1.4 go) and Precambrian (0.5 go< g < 1.9 go) These limits can be used to put constraints on hypotheses involving Earth expansion and changes in the universal constant of gravitation.