Rock in your landscape can add texture and contrast like no other material. It can be as simple as using gravel for a walkway or ground cover. Larger stones can be used create walls and decorative borders. Or, rock can take center stage in the form of huge boulders that make a dramatic centerpiece. There are several types of rock that can be used as landscape material, each with its own unique properties and applications.
Shale and Slate
Shale and slate are sedimentary rocks, formed from layer upon layer of soft silt and mud. Over millennia, the mud was compressed under great pressure to form rock. Shale and slate are relatively soft forms of rock, shale being somewhat softer. Shale and slate come in colors ranging from reddish hues to greyish black. Because these rock types are formed in layers, they can be split to form large, flat surfaces. This makes shale and slate excellent for flagstone walkways and masonry. Shale and slate can also be crushed to form a fine gravel for walkways, or a heavy, decorative mulch.
Sandstone is another sedimentary rock created by sandy soils from ancient oceans being compressed over millions of years. Sandstone is a very soft rock and is relatively easy to shape by hand. It comes in a variety of colors from almost pure white to reds, yellows or even blueish or purple hues, often with bands or swirls of color. Large sandstone boulders make excellent centerpieces. Smaller rocks can be used for wall material. Some sandstones will also split, similar to slate or shale, and can be used for walkways.
Granite is a metamorphic rock that is very hard and durable. Granite is made up of a matrix of tiny crystals, each with its own color and texture. Granites range in color from very light, whitish rock to browns, reds, blacks and grays, and even pink. Granite adds texture to a landscape as accent boulders, coping materials, wall masonry, cobblestones and gravel.
Marble and Limestone
Limestone and marble are made from ancient calcium deposits and are relatively soft stone. Limestone can be used for walls and stairs, as in masonry. Crushed limestone is also available for walkways and as a landscape cover material. It comes in a wide variety of colors and patterns.
Marble is a finely-grained form of limestone. It can be more expensive than other types of rock. It can be polished to a high sheen, and is often used for statuary or other decorative works.
Lava rock is exactly what it sounds like, rock that is made of hardened lava. Usually dark, rusty red or black, lava rock is coarse and heavily textured with a foamy appearance. It can add a high level of contrast and can really stand out in a landscape. Crushed, it is often used in place of organic mulches. Larger boulders are quite light and can be easily positioned as accent pieces in the landscape.