Department Of Geography, Surroundings And Geomatics
Paleogeographic reconstructions of the New Zealand landmass and offshore sedimentary basins from the Cretaceous to present day are illustrated in a series of eight maps (after King et al. 1999, King 2000). The deep drilling of the ocean floor that was begun in 1968 made attainable the direct reconstruction of the paleogeography of the oceans. By the end of the Paleozoic, many of the earlier oceans had been closed because the continents collided to kind the supercontinent Pangaea, centered on the equator.
On a world scale, collisions have decreased the size of continents and expanded the dimensions of ocean basins. The international journal Palaeogeography, Palaeoclima-tology, Palaeoecology, which has been printed in Amsterdam since 1965, offers with questions of paleogeography.
In the 1950’s the paleomagnetic technique for determining historical latitudes was launched, and the examine of variable-sign linear magnetic anomalies in the oceans was initiated. Different necessary sites within the United States include the Dakota and Potomac groups, which assist place the earliest flowering plants in the early-middle Cretaceous interval.
Simply prior to the top of the Mohawkian Stage (early Late Ordovician), the shallow shelf deposits of northeastern United States had been being modified rapidly by the onset of Taconic tectonism. The study of plant fossils has supplied considerable details about the range and evolution of crops-including their origins, doable extinction, modifications over time, and rates of evolution.
The map at the left is a reconstruction of North America from 75 million years ago (Campanian Stage). Assets containing specific information about and primary knowledge for key Cretaceous geographic options. Among such maps were J. Marcou’s maps of the world and European Russia throughout the Jurassic period (1860) and J. Dana’s map of North America through the Cretaceous (1863).