The Middle to Late ordovician Taconic orogen was eroded during early silurian times, shedding early silurian clastic sediments, including molassic sands and gravels. Erosion of the Taconic orogen was fairly complete by middle silurian times when the sea was again able to advance over the lands once covered with mountains.
The silurian and Devonian atmosphere was strongly oxidizing, as indicated by abundant iron oxides in rocks of this age. sediments deposited on the North American continent at this time include abundant evaporates, so the climate was likely warm for this period. In addition there are numerous reefs from North America, and modern-day reef systems form only at +/- 30° of the equator. interestingly, the paleobiogeographic record shows that similar plants existed virtually everywhere at this time, suggesting that the Devonian climate was uniform on a near-global basis. Comparison with many past climates reveals that many were much warmer than Earth's present climate, lending support to the idea that the Earth can support very warm climates, and any changes that the planet may be experiencing presently from global warming could lead to major changes in planetary ecosystems.
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