Maes Down

Also within

Somerset County

Condition (Natural England)

Geology & landscape

Geological Period: Jurassic · Rock Type: Limestone

Description

Area, 0.2 ha. 0.4 ac. Description The rocks seen at Maes Down were laid down about 190 million years ago, during the Upper Pliensbachian and Lower Toarcian Stages of the Jurassic Period of geological times, when this part of Britain lay beneath the sea. The special interest of the site is due to the presence of a limestone band known as the 'Junction Bed' which contains a rich fauna of fossil ammonites and which enables geologists to make deductions about the geography of the Mendip area during early Toarcian times. The Junction Bed is well seen over a wide area of Somerset and Dorset and its presence in the Mendiparea clearly shows that the area lay in a similar environment to that which existed further south. Earlier in the Jurassic, however, this was not the case and there is evidence that the Mendip area stood above the early Jurassic sea as an archipelago. The fact that by Junction Bed times the environment on Mendip was similar to that of the main marine area gives geologists an indication as to the time when the Mendip area was eventually inundated by the sea. This makes Maes Down of considerable importance for reconstructing the changing geography of the Mendip area during early Jurassic times.