West Virginia – Rubbleland …Surprising Soil Characteristics

Stephanie Connolly, MNF Soil Scientist and Mike Jones, NRCS Soil Scientist
Image of a shovel that has dug down to a depth about as deep as its handle.

(USDA Forest Service photo by Adrienne Nottingham)

Many people have the opinion that the term Rubbleland means a pile of rocks with nothing growing or even able to grow there. After more than 5 years of shovel-breaking, rock- breaking, and back-breaking work, soil scientists in West Virginia know this is just not true. It might appear to be a pile of rocks on the surface, but there are a plethora of soil, plants, and animals found within the nooks and crannies between these rocks! One example is the Cheat Mountain Salamander, which is a federally-listed threatened species. This salamander’s habitat and native range includes areas of Rubbleland within the Central Appalachian Highlands of West Virginia.

Soil surveys consider Rubbleland areas as “miscellaneous areas” and little soil mapping effort was dedicated to describing these areas when these they were first mapped because these landscapes and soils did not support agricultural activities. Rubbleland is defined as areas of cobbles, stones, and boulders commonly at the base of mountains, or left on mountainsides by glaciation or periglacial processes. Developing soil properties and resultant interpretations is of particular interest to the US Forest Service, Monongahela National Forest (MNF) staff, since much of the Rubbleland mapping occurs throughout the Forest.

West Virginia is “blessed” with many areas that meet the definition of Rubbleland, with over 400 delineations. Areas mapped as Rubbleland in West Virginia are found in Hampshire, Mineral, Monroe, Tucker, and Randolph Counties, with much of it residing within the MNF. Thanks to the hard work of the MNF Soils Resource Program staff, the Morgantown, WV Soil Survey Office (MLRA 127) staff, and West Virginia State Office staff, the soil survey program is adding valuable information to better understand the importance of these areas.

Rubbleland polygons tend to occur below ridges that are “capped” by the Tuscarora Sandstone. Geologists call these materials scree, or talus, and the landforms on which they occur are called talus slopes. There are also many areas of Rubbleland occurring on the very resistant sandstone formations in the Pottsville Group.

Photo of soil below rock. A measuring tap shows depth at 40 inches

(USDA Forest Service photo by Adrienne Nottingham)

Rubbleland map units have interesting soil characteristics due to large rock fragments at or near the ground surface. The wavy boundaries and discontinuous horizons of the soil profiles beneath the rocks are examples of these distinguishing features.

Soils forming from the associated coarse sandstone parent materials do not always produce the sandy-textured soils that one might expect. The finer soil textures often found in the subsoil, such as fine as silty clay loam, make these Rubbleland units interesting from a soil interpretation and soil genesis viewpoint.

High volumes of rock fragments with random orientation facilitate preferential flow, which causes differential soil development. Pockets or bands of organic and iron compounds are often irregularly distributed within fine-earth material, creating properties of a spodic horizon.

Some spodic horizons can have a reddish hue which denotes the presence of amorphous iron oxide compounds. These iron compounds, and often associated aluminum compounds (sesquioxides), can create strong cementation (Bs horizon). Other spodic horizons can have a very dark to nearly black color below an eluvial (E) horizon, which indicates the presence of mobile amorphous organic compounds (Bh horizon). The mixing of sesquioxides and organic compounds often occurs (Bhs horizon).

Another property of these soils is very low pH, due to the parent material, vegetation, and high precipitation. The parent material is naturally low in base cations. Plant communities, typically consisting of red spruce, laurel, rhododendron, hemlock, and other less abundant species, produce a litter layer which creates more acidic conditions through decomposition. The pH values measured during the Rubbleland sampling ranged as low as 2.7 when red spruce is dominating the forest around the site.

Conducting investigations in Rubbleland areas is very difficult due to the quantity and size of the rocks and the remoteness of these delineations. For these reasons, along with the historical lack of emphasis placed on non-agricultural lands for soil mapping, little information on infiltration or saturated hydraulic conductivity exists for these soil types and the map units. The information generated from this project will add a great deal to the understanding of soil properties and interpretations of miscellaneous areas and will assist land managers on the Monongahela National Forest.

What will be done with this new information? Interpretations that are currently available for Miscellaneous areas such as Rubbleland, in most cases, return no results (i.e. not rated) when run on miscellaneous areas. These new data on the physical and chemical properties of the underlying soils will enable soil components to be developed and creation of new soil series is likely. This will provide interpretations for these areas. Currently, the National Cooperative Soil Survey is participating in a study to produce even more data and provide information for future management interpretations.