Jurassic Coast cliffs, spanning the Mesozoic, documenting 185 million years of geological history. The site can be best viewed from the sea, when the dipping nature of the rock strata becomes apparent. In East Devon, the coastal cliffs consist of steep cliffs of red sandstone from the Triassic, and at Budleigh Salterton, the gravel cliffs contain red quartzite pebbles which accumulate on the beach below as Budleigh pebbles, locally protected.Further east at Ladram Bay, more sandstone cliffs give rise to spectacular red sandstone stacks. Around Lyme Regis and Charmouth the cliffs are of Jurassic clays and shale, and landslips are common. Chesil
Cretaceous local subdivisions are still in use. As with other older geologic periods, the rock beds of the Cretaceous are well identified but the exact age of the system's base is uncertain by a few million years. No great extinction or burst of diversity separates the Cretaceous from the Jurassic. However, the top of the system is sharply defined, being placed at an iridium-rich layer found worldwide that is believed to be associated with the Chicxulub impact crater, with its boundaries circumscribing parts of the Yucatán Peninsula and into the Gulf of Mexico. This layer has been dated at 66.043 Ma.