Geology of Kent into northern France. The fold arises from the continuing Alpine orogeny and results in the general northward dip of the rock strata in most of Kent. There are extensive spreads of coastal and estuarine alluvium on the Thames Estuary coast, in the low ground surrounding the Isle of Thanet and across Romney Marsh. Alluvium also floors the valleys of the River Medway and Stour. 'Clay-with-flints' is a commonly occurring deposit across the North Downs which is a product of periglacial conditions during the last ice age. Loessic deposists, of aeolian origin i.e. windblown, are common in east Kent, especially on
Geology of the Lassen volcanic area south and east, reaching the head of Warner Valley. By this time, the park's eastern portion had been transformed into a relatively flat plain. The activity was followed by an eruption of the Eastern basalts from volcanoes east of the park. These thick flows have subsequently eroded to produce rugged hills that limit the park on the east. Taken together, these various flows built the lava plateau that the Lassen volcanic area is located on. From 600,000 to 400,000 years ago, eruptions built a large conical stratovolcano called Mount Tehama (also called Brokeoff Volcano) in what is now the southwest