Potential effects of plate motions on climate

Just before the end of the Cretaceous, a drop in eustatic sea level caused exposure on all continents.

The flavor of the Mesozoic would be lost without some general sense of Mesozoic paleoclimates or ancient climates. How can we know about past climates? It might seem as if climate is a bit like performance art: if you are not there to experience it, it's gone. Deposition, after all, leaves physical evidence. Climate, on the other hand, might seem to be a more ephemeral quantity. It turns out, though, that just as one can record the sound of a muscial performance, so earth has recorded traces that allow us to infer at least aspects of past climates. The record suggests that, not surprisingly, climates have not remained constant throughout earth history: they, like everything else, have changed through time.

Why even suspect that past climates differed from those of today? Distributions of the land masses as well as the amount and distribution of the oceans on the globe drastically modify temperatures, humidity, and precipitation patterns. In the following, we explore this, comparing the extreme case of the continents coalesced into a single landmass (see Figure 2.5) with the equally extreme (but more familiar) case of the continents widely distributed around the globe (Figure 2.10).

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