River gravel is a name given to gravel

Gravel

Gravel is composed of unconsolidated rock fragments that have a general particle size range and include size classes from granule- to boulder-sized fragments. Gravel can be sub-categorized into granule and cobble...

 composed of small pieces of rounded stone of various colors, usually no larger than a large coin. It is named for the effect of many years of rounding of the edges of the stones due to a flow of water over it, as often takes place in a river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

. River gravel is often used in outdoor settings, such as a park walkway.

When a hard surface is also desired, river gravel is often set in a concrete

Concrete

Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...

 aggregate

Construction Aggregate

Construction aggregate, or simply "aggregate", is a broad category of coarse particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. Aggregates are the most mined material in the world...

 mix. Owing to much higher cost than either asphalt

Asphalt

Asphalt or , also known as bitumen, is a sticky, black and highly viscous liquid or semi-solid that is present in most crude petroleums and in some natural deposits, it is a substance classed as a pitch...

 or concrete pavement, the use of river gravel is generally limited to places where the appearance and/or its lack of sharp edges (when used alone) is of primary importance.

The American

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 National Park Service

National Park Service

The National Park Service is the U.S. federal agency that manages all national parks, many national monuments, and other conservation and historical properties with various title designations...

's bucolic Colonial Parkway

Colonial Parkway

Colonial Parkway is a scenic 23-mile parkway linking the three popular attractions of Virginia's Historic Triangle of colonial-era communities, Jamestown, Williamsburg, and Yorktown...

, linking the three points of Virginia's Historic Triangle

Historic Triangle

The Historic Triangle is located on the Virginia Peninsula of the United States and includes the colonial communities of Jamestown, Colonial Williamsburg, and Yorktown, with many restored attractions linked by the Colonial Parkway in James City and York counties and the City of...

, has a road surface of river gravel set in concrete aggregate. Built between 1930 and 1957, the Colonial Parkway is possibly the longest roadway open to the public which is surfaced of the material.

River gravel is also occasionally used for landscaping purposes and placed by landscape architect

Landscape architect

A landscape architect is a person involved in the planning, design and sometimes direction of a landscape, garden, or distinct space. The professional practice is known as landscape architecture....

s in non-traffic areas of high visibility. It may be used with many plants and shrubs because the rounded surfaces ensure rain and other water will soak through to reach the roots for necessary nurture.