Decomposed Granite (DG):

Decomposed granite resembles crushed stone, although it erodes into angular pieces through natural processes. Decomposed granite, with or without fines, compacts relatively well. When combined with fines and compacted, decomposed granite is a popular surface choice for trails, parking areas, parking pads, and living areas in campgrounds. Some designers group crushed stone, crushed gravel, and decomposed granite under the single term angular rock because these materials have many characteristics in common. All are excellent for many surfaces used by horses and mules.

Sand:

Sand is fine granular material produced by the natural disintegration of rock. The USCS says that sand is material that passes a No. 4 (4.750-millimeter) sieve, but is retained on a No. 200 (0.075-millimeter) sieve. Sand drains well and creates a soft trail tread for stock. When used alone, sand is easily eroded or replaced by other materials and can be dusty. Often, sand is combined with clay and gravel or other materials to improve its drainage or prevent too much compaction. If sand is applied more than 3 inches (76.2 millimeters) deep, it can strain an animal’s tendons and ligaments. Over time, horses that eat or breathe sand can contract sand colic, a serious illness. Sand should not be used in areas where horses and mules eat or where they spend a lot of time.