Crow Dog Native Ferns and Gardens
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Crow Dog Gardens
Regional and Local Geographic History
Crow Dog Native Ferns and Gardens is located about one mile, as the raven flies, from Table Rock Mountain (pictured above) near the North Carolina border in western South Carolina. Table Rock Mountain's elevation is 3124 feet, and its geographic position is on the Blue Ridge Front regionally called the Blue Wall. The Brevard Fault Zone that is the ancient and major suture between the eastern Piedmont Provence and the Blue Ridge Provence runs northeast/southwest close by.

The ecological diversity in the region is very rich in part because of the diverse geology and geomorphology. In many respects the region is a steep ecological gradient and a transition zone between southern and northern plant communities and species. Plant communities and species are influenced by two major factors: the underlying and exposed geology of the region, and current and historic land use.

In general, the rocks of the region are of two types: meta-volcanic rocks and meta-sedimentary rocks that are thought to have been surface deposits when the Piedmont was an ancient island arc separated from the North American continent; and younger meta-plutonic rocks that intruded into the later buried meta-volcanic and meta-sedimentary rocks. Both rock types are now exposed on the surface after thousands of feet of the once towering Appalachian Mountains were eroded away filling the eastern Coastal Plain with deep sediments.

Surface exposure and weathering of these rocks produced the soils of the region. Over time and before widespread agriculture, regional soils were very rich and supported a wide diversity of plant species and plant communities. In broad terms, the region contained dark, rich, and deep topsoil (A horizon). That topsoil varied widely in pH. The A horizon soils derived from many of the meta-volcanic and meta-sedimentary rocks, that are high in Calcium and Magnesium, had circum-neutral pH around pH of 7 ( the Poor Mountain amphibolite pictured at right). In contrast, A horizon soils derived from the plutonic rocks, that are mostly granitic in composition and high in Aluminum, had pH in the 4.5 to 5.5 range (the Table Rock Granite at right).

A geologic map of Wadakoe Mountain (app. 5X6 miles) about 5 miles from Crow Dog. The blues are granite composition rocks, and the purple and light green are meta-volcanic rocks. This area is one of the most botanically diverse places in North America.
Table Rock granite gneiss: subsoil (pH ~4.8), and A horizon soil (pH ~5.1) Poor Mountain amphibolite: subsoil (pH ~5.8, A horizon (pH ~6.8)

And then there were transition soils where different rock types were juxtaposed. Only small remants of these rich soils are present today in areas where agriculture has historically been prevented because of topographic relief and other factors. Fortunately, in the western Carolinas, many of these remnants are now in public hands, and preservation is possible. Representative soil analyses for local remnant granitic and amphibolite A horizon soils are depicted below.

Crow Dog Native Ferns and Gardens is situated on land that was heavily farmed and pastured in the past. Historic nonrestorative land use has resulted in the total loss of A horizon soils. This is typical of vast areas of the eastern Piedmont. Crow Dog's wooded land has both meta-volcanic and granitic composition rock substrates with corresponding B horizon subsoils and very thin to no A horizon soil. The subsoil of the meta-volcanic rock is a sandy dense red clay, and the subsoil of the granitic rock is light buff-colored, and very sandy clay. Both subsoils are widespread surface soils of the Piedmont.

This is a sandy acidic floodplain underlain broadly by Caesar's Head Granite Gneiss that is high in Aluminum content. Floral diversity is approximately half that of the much higher pH soils of the Wadakoe Mountain amphibolite pictured at right.
This outcrop is amphibolite that is high in Calcium and Magnesium content, and therefore the soil has higher pH. The thick topsoil at this site is high in
organic matter and micro-organisms. Through the decomposition of the organic matter, organic acids are produced that reduce primary weathering
clays and release Ca and Mg into the soil solution.