The tar pits found at Rancho La Brea and McKittrick were both formed during the last Ice Age. Evidence for the original environment can be acquired from the ancient sediments and the fossils found within the locality. The ancient sediments provide excellent information about the deposition environment, for example: terrestrial, marine or freshwater; relative energy; chemical condition at and after the time of deposition; original topography and to some extent climate.
The climate is also indicated by the local fossils (providing there has been little or no transport). The fossils are compared to their nearest, living relatives, which gives an idea about what the fossils would have looked like and how they might have lived.
From the sedimentological information and the fossil evidence collected from Rancho La Brea and the McKittrick Tar Pits it is clear that the main environment was represented by plains and savannah with some mountainous areas. The climate was cooler and more humid than the present climate.
The picture below shows the original environment in Europe during the Ice Age. The savannah in which the La Brea tar pits were formed occurred SW of the ice sheet and as a result the environment was drier than the forests.
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