Bristol Impact Layer
(Bristol, England, United Kingdom)
Samples of the only impact layer found in the UK - found at a single locality that is no longer in existence. The impact layer was found in Triassic mudstones & siltstones and has been dated at 214 million years. It consists of a close packed layer of mm-sized green spherules that were once glass beads but have now be altered to clays. Many of the beads are hollow containing bubbles, and are accompanied by shocked quartz grains. The age of the impact layer indicates it represents debris blasted from perhaps one of the best known of large terrestrial craters - the 100 km diameter Manicouagan structure in Canada. Two hundred and fourteen million years ago, Canada and the UK were only 2000 km apart and the glass spherules, formed as molten droplets condensed from the Manicouagan impact plume, rained down fire over the red deserts of Bristol, smothering the landscape. The find locality, a quarry in Bristol, has now been filled-in and lost forever.