Chase, C.G., Gregory-Wodzicki, K.M., Parrish, J.T., DeCelles, P., 1998, Topographic history of the western Cordillera of North America and controls on climate, in Crowley, T.J., and Burke, K., Tectonic Boundary Conditions for Climate Model Simulations: Oxford Monographs on Geology and Geophysics No. 39, Oxford University Press, p. 73-99

Paleontologic evidence depends mostly on the effect of elevation on local climate, and the effects of that climate preserved in organisms. Climate-based paleobotanical methods using leaf morphology provide most of the quantitative estimates of paleoaltitudes, and the smallest estimated errors. Care is needed to avoid circularity in using climate-based paleoelevations as boundary conditions for climate models.

Paleogeographic constraints can give general impressions of regional topography, but they are hard to quantify. Tectonic principles are essential in understanding the origin of topography, but it is difficult to extract precise estimates of elevation from preserved structures. Careful reconstruction of thrust belts can give clues to regional topographic gradients, especially when carefully related to sedimentological data. Sediments themselves can be used to constrain paleoelevational gradients, and they are particularly useful in providing the position of ancient sea level. New, not yet proven methods that depend more directly on air pressure include in-situ cosmogenic isotopes and basalt vesicularity.

We have compiled available paleoelevation data into Middle­Early Miocene (14­22 Ma), Oligocene­Late Eocene (22­45 Ma), Middle­Earl