Stone Walls

By Michael Gaige

As a result of its geology and history, Oak Spring contains over two miles of stone walls with a construction period spanning settlement to recent times. Original field stone, exposed during the landscape’s transition to agriculture, lie stacked in the same lines as when they were laid. Other walls existed 100 years ago but have been repurposed to other areas. The Mellon period left its mark with tightly fit, sharp walls along the road and gateways.

In general, Virginia lacks a strong tradition of stone fencing when compared to regions north of the glacial boundary. Nonetheless, three eastern regions are recognized for concentrations of stone walls: New York State and New England; Kentucky’s Bluegrass Region; and Virginia’s northern Piedmont and Blue Ridge (Lewes and Houston 2004).

Background

Stone walls are most often built as fences to keep animals in, or out, of something. As a fence, a wall needs to be 4 feet tall, and may be composed entirely of stone, or as a shorter wall with a wood or wire rail on top. A lawful fence in Virginia in 1872 had to be four feet high (Lewes and Houston 2004). The lack of glacier-deposited stone, and an abundance of trees, meant most fencing was made of wood. The split rail, zigzag, or “worm fence” was the standard fence in Virginia for generations. This was followed later by the post and rail fence – popular until late 1800s. In 1871, 85 percent of fences in Virginia were wood (Lewes and Houston 2004). Although stone was absent from the coastal plain (as a result of geology) it was available from the Piedmont, westward.

Oak Spring's Stone Walls. Dry stacked wall of original field stone in red; original field walls, rebuilt in recent times with some mortar added in purple; contemporary walls of Mellon era with imported stone, some chinking, and hidden mortar in green.

Some stone walls are not built as fences at all; many walls are built as repositories for unwanted stones taken from agricultural fields. Such stone dumps may resemble little more than a pile (called a clearance cairn) or may result in an extensive, well-stacked wall. Stacking them frees up pasture surface area for grasses. In Northern Virginia many walls developed haphazardly; cleared fields exposed regolith and the stones were piled up.

This changed when affluence arrived. Rock walls were expensive to build and their elegance became a badge of wealth. It’s unclear whether this happened during the region’s first wave of wealth when settlers, prospering on rich soils, became middle-upper class – or whether it was the second wave of wealth when affluent northerners bought up old estates after the Civil War. Nonetheless, walls went up throughout Loudoun and Fauquier County from settlement onward, and especially during Mellon times.

Stone walls along Peach Tree Lane

Autumn von Plinsky

Two Miles of Stones

Most of the stones in Oak Spring’s walls are greenstone (meta-diabase) from the basaltic dikes that emerged through the old granites back in the Paleozoic. I estimate most of Oak Spring’s fieldstone walls are 90% greenstone and 10% granite. This corresponds closely to the ratio of rock outcroppings of the two rock types found at Oak Spring (see rock outcrop section). The Parent Material map created by Jim Sawyer for the Type 1 Soil Survey shows similar proportions.

The diabase rocks are irregularly shaped cobbles, with mostly rounded, weathered surfaces. Cobbles are generally 4 to 12 inches – tennis ball to volleyball size with the largest stones tending to lie at the bottom of a wall. The granite rocks stand out as white, angular rocks in a wall of otherwise dark, or orange, irregularly rounded stones. The ground was prepared and leveled before laying stone, but stones don’t rest deeply below.

The walls on Peach Tree Lane and the parallel wall by the Broodmare Barn have American chestnut rounds stacked within the wall. These were placed to guide consistent wall width and taper during construction. I have not found anyone who is familiar with this style (or a name for it). These two walls are original location dry-stacked fieldstone walls composed primarily of diabase. In recent times they may have served as fencing for horses. But is it likely that the stones originated from the adjacent fields. Rocks were dry stacked, with no chinking. Some sections have very little lichen growth so must have been rebuilt in recent times when sections collapsed or leaned. Lichen growth could be used to relatively age the walls. Heavy lichen coverage is found on rocks in walls that have remained standing for many decades. There is very little lichen growth on the roadside walls made from quarried, imported (regionally) stones.

The short section of wall in the woods above Goose Creek (at the south end of the forest) was unfortunately quarried away in 2017 and placed as rip-rap at the spillway base of the Lower Pond dam.

RED LINES SHOW ORIGINAL STONE WALLS at Oak Spring in 1937 as interpreted from this aerial photograph. It is difficult to discern walls from wood fences in the imagery.

Dry stacked, local field stone, wall above the Broodmare Barn. Note the limited lichen growth.

Quarried stone in a Mellon era wall along the road. These walls have mortar and chinking. The top rails are American chestnut.

Original dry stack wall in the forest slope down to Goose Creek. This wall has a curious history; see text.

Original dry stack wall of local field stone along Peach Tree Lane. Note the lack of lichen growth and the American chestnut guides in the middle.

A wall from the cemetery. These rocks appear granitic, but not rounded as the local field stone. Note here the amount of lichen growth on the rocks suggesting it has been in place for some time.

This dry stack wall occurs along the northeast boundary. Most of this wall is in fine shape, however, seen here a fallen tree is collapsing a portion. Trees are the primary threat to walls.

In researching Oak Spring’s deed history at the county office, I found numerous references to “stone fences” in written records. Robert Fletcher’s will dated to 1841 contains a map showing existing walls on Peach Tree Lane and the fence on the northeast boundary going from upland fields through the steep forest to Goose Creek (it also shows the forest). Going farther back, local deeds from the 1810s mention stone fences here and there as part of the meets and bounds description, but it is unclear where these fences are (on or off Oak Spring). Nonetheless, considering the ~1820s date of the house, and these deed references, I am confident that Oak Spring’s first generation walls date to early 1800s from in their existing location, making them ~200 years or older.

It would be interesting to research the amount of original stonewall built per area of land (in linear feet per square mile, for example). In other words, how much rock was available and how many miles of wall were built in each square mile of land? At Oak Spring alone, the local fieldstone yielded 8,500 linear feet over 260 acres. The forest at Rokeby, which has never been cleared for pasture or crops, might reveal how much stone is contained in upland soils around Upperville, and how deep it lies below ground.

Most likely the walls were built over time as the land was worked and settled. As plowing uncovered stones, they were added to the walls. After Paul Mellon took ownership, walls were rebuilt, repurposed, and/or replaced. Lichen growth weathering may be the only way to interpret if a wall has been significantly altered in the past.

I believe the original dry-stacked walls at Oak Spring were built as stone dumps to remove stones from fields. A study in adjacent Warren County arrived at the same conclusion (Lewes and Houston 2004).

This hypothesis, however, is challenged somewhat by the section of wall in the forest that runs down the steep slope to Goose Creek. Clearly, no one was farming that slope; the topography is too challenging and the old growth trees indicate the site has always been forested. Therefore, the wall must have been created as a fence to keep animals on one side or the other. As shown in plat maps, that wall was a boundary between the Fletcher farm (Oak Spring) and the John Wren Farm to the north.

But with both sides of the wall having always been forest the full history is unclear. The wall must have been a fence that doubled as a property line. This would have made a more permanent boundary than using the wood that was obviously available in the forest. The slopes on the adjacent property hold abundant loose fieldstone; building a wall would have been simple. The woods on Oak Spring’s steep slope were grazed so a fence would have been needed. As the 1841 map from Robert Fletcher’s will shows, trees were in short supply and thus may have necessitated the use of stone for fencing.

Oak Spring’s walls are one of the best and most treasured features on the property. They are unique for Virginia, and having so many vintages of wall totaling over 11,000 linear feet in a relatively small area is special.