Silt fence top of the structure; requiring another silt fence above or below it (creating a new ponding area), or for the silt fence to be removed, the sediment removed or spread out, and a new fence installed. The fence is not designed to concentrate or channel stormwater. The fence is installed on a site before soil disturbance begins, and is placed down-slope from the disturbance area. Sediment is captured by silt fences primarily through ponding of water and settling, rather than filtration by the fabric. Sand and silt tends to clog the fabric, and then the sediments settle in the temporary
Fern House Gravel Pit no public access. Fern House Gravel Pit Fern House Gravel Pit is a 1.3 hectare geological Site of Special Scientific Interest in Fern, near Bourne End in Buckinghamshire. It is also a Geological Conservation Review site. This site exposes the Pleistocene Taplow Gravel formation, and may help to elucidate a poorly understood period in the history of the River Thames, between glacial Anglian stage, around 450,000 years ago, when the river was diverted south to its present course, and the warm Ipswichian around 120,000 years ago. Fossils found at the site include straight-tusked elephants and mammoths. The site is on