Rice grows on a variety of soils like silts, loams and gravels. In Flanders, sands, gravels and marls predominate, covered by silts in places. The gravels, sandstones and clay were all associated with alluvial deposits. Quincy Basin is filled with the eroded gravels and silts from the Coulee. Sedimentary gravels are found in the form of the alluvial Mangas Valley gravels. There are small areas of Tertiary basalt with buried river gravels and lake sediments. Originally tin was found as alluvial deposits of cassiterite in the gravels of stream beds. The outer coastal plain consists of unconsolidated Tertiary deposits of sands, silt, and gravels. The valley floor consists primarily of alluvial fans composed of small poorly sorted gravels. Kames are small hills that consist of sediments ranging from sands to gravels. Soil textures range from coarse, rocky gravels to fine, compacted clays. Siliciclastic rocks initially form as loosely packed sediment deposits including gravels, sands, and muds. The Southern Lowlands consist of Miocene and Pliocene sands, clays, and gravels. The chalk gently slopes south and dips under clays and gravels. Coarse-grained soils, mainly gravels or sands, are graded as either well graded or poorly graded.