Alluvial floodplains have developed in the lower park on deposits of quaternary alluvium. Soil consists of sediments such as alluvium, teris, brown sands, etc. The soil consists of several metres of alluvium or silt deposited by the Seine. The lower basin is made up of young sediments, including laterite and recent alluvium. Soils washed from slopes were deposited in valley bottoms as a rich, swampy alluvium. Overlying these are various types of Quaternary unconsolidated deposits such as alluvium, colluvium, and dunes. The Condamine River flood plain is noted for its good soils formed by basaltic alluvium. Area creeks including East Cache Creek contain deposits of Quaternary alluvium. The appellation has a range of gravel, alluvium, clay and limestone soils. It taps groundwater from the wadi alluvium and some from the bedrock. Most settlements in ancient Egypt were situated on the alluvium of the Nile floodplain. When a river breaks its banks, it leaves behind layers of alluvium (silt). Streams can carry sediment, or alluvium. According to the United States Geological Survey, Brownsville's soils are primarily alluvium and windblown deposits. The soils of Stellenbosch range from dark alluvium to clay.