Arkansas is a land of mountains and valleys, thick forests and fertile plains. The so-called Lowlands are better known by names of their two regions, the Delta and the Grand Prairie. The Arkansas Delta is a flat landscape of rich alluvial soils formed by repeated flooding of the adjacent Mississippi. Further away from the river, in the southeast portion of the state, the Grand Prairie consists of a more undulating landscape. Both are fertile agricultural areas.

The Delta region is bisected by an unusual geological formation known as Crowley's Ridge. A narrow band of rolling hills, Crowley's Ridge rises from 250 to 500 feet (150 m) above the surrounding alluvial plain and underlies many of the major towns of eastern Arkansas.

Northwest Arkansas is part of the Ozark Plateau including the Boston Mountains, to the south are the Ouachita Mountains and these regions are divided by the Arkansas River; the southern and eastern parts of Arkansas are called the Lowlands. All of these mountains ranges are part of the U.S. Interior Highlands region, the only major mountainous region between the Rocky Mountains and the Appalachian Mountains. The highest point in the state is Mount Magazine in the Ozark Mountains; it rises to 2,753 feet (839 m) above sea level.

Arkansas is home to many caves, such as Blanchard Springs Caverns. It is currently the only U.S. state in which diamonds are mined.

Lumber or timber is a term used to describe wood, either standing or that has been processed for use - from the time trees are felled, to its end product as a material suitable for industrial use - as structural material for construction or wood pulp for paper production. In the U.K. and Australia, "timber" is a term also used for sawn wood products (that is, boards), whereas generally in the United States and Canada, the product of timber cut into boards is referred to as lumber. In the United States and Canada sawn wood products of five inches (127 millimeters) (nominal size) diameter or greater are sometimes called "timbers".

Lumber is supplied either rough or finished. Rough lumber is the raw material for furniture making and other items requiring additional cutting and shaping. It is available in many species, usually hardwoods. Finished lumber is supplied in standard sizes, mostly for the construction industry, and is primarily one of a few coniferous (needle-bearing) species such as pine, cedar, hemlock, fir or spruce.