Missouri is divided into four major land regions. The Dissected Till Plains, lying north of the Missouri River and forming part of the Central Plains region of the US, comprise rolling hills, open fertile flatlands, and well-watered prairie. The Osage Plains cover the western part of the state, their flat prairie monotony broken by low rounded hills. The Mississippi Alluvial Plain, in the southeastern corner, is made up of fertile black lowlands whose floodplain belts represent both the present and former courses of the Mississippi River. The Ozark Plateau, which comprises most of southern Missouri and extends into northern Arkansas and northeastern Oklahoma, constitutes the state's largest single region. The Ozarks contain Taum Sauk Mountain, at 1,772 ft (540 m) the highest elevation in the state. Along the St. Francis River, near Cardwell, is the state's lowest point, 230 ft (70 m).
Including a frontage of at least 500 mi (800 km) along the Mississippi River, Missouri has more than 1,000 mi (1,600 km) of navigable waterways. The Mississippi and Missouri rivers, the two largest in the US, respectively form the state's eastern border and part of its western border; Kansas City is located at the point where the Missouri bends eastward to cross the state, while St. Louis developed below the junction of the two great waterways. The White, Grand, Chariton, St. Francis, Current, and Osage are among the state's other major rivers. The largest lake is the artificial Lake of the Ozarks, covering a total of 93 sq mi (241 sq km).
Missouri's exceptional number of caves and caverns were formed during the last 50 million years through the erosion of limestone and dolomite by melting snows bearing vegetable acids. Coal, lead, and zinc deposits date from the Pennsylvanian era, beginning some 250 million years ago. The Mississippi Valley area is geologically active: massive earthquakes during 1811 and 1812 devastated the New Madrid area of the southeast.