Classification - Background Text

This may look like a stone wall but it isn't. Its molded plastic. Note flat side nearest the viewer). If it were a stone wall, it would be a quarrystone, normal,freestanding double wall.

CAUTION: This taxonmy is a work in progress and has not yet been peer-reviewed by experts. The SWI coordinator is preparing a manuscript for publication in the international journal Geoarchaeology.

Definition of the Class "Stone Wall"

A stone wall is an object composed of stone more than four times longer than it is wide, continuous along its length, and in which the stones either rest above one another or about two feet high.   Part of this definition is based on material.  Synthetic stone is included because there is a complete continuum between porcelain-quality ceramic bricks, and artificial stone, made to look like the real thing.  Besides, many roadside walls contain fragments of broken up brick, bituminous pavement and/or concrete. Finally, natural puddingstone (sedimentary conglomerate) and concrete often closely resemble each other.  The dimensions matter as well.  Arbitrarily, a wall must be at least four times longer than it is wide, ratio chosen after informal surveys of the historic literature and of potential users.   What’s important is not the ratio itself, but that it is consistently  used.  Finally, there is structure.  Some of the most common features that the majority of people consider walls are little more than a low row of stones stacked above one another, many not more than a foot above the ground.  At the same time, the same people would exclude row of small boulders bordering a driveway or a garden.

There are three key elements required to identify a stone wall: Continuity, meaning that there are no conspicuous gaps between the stones along the line of the wall; Elongation, here arbitrarily defined as having a length more than four times its width (regardless of height); Height, here defined either in terms of construction (stones rest one above another), or an arbitrary height, here set at the approximate height of an adult human knee, which is about two feet.

Defining a stone wall raises the related questions:  Are there different “types” of stone walls?  Yes.  Are stone walls a “type” within some larger constellation of objects?   Yes.  Similar questions were asked by natural historians as the individual sciences developed. In biology, the answer was to group all living things into categories of different rank, ranging from the largest to the smallest, from kingdom, order, class, family, genus, on down to species. I propose something similar for stone wall science, something broad enough to include, rank, separate, and name all manner of stone walls, ruins, piles, and odd stones.  Creating a taxonomy is a critical step in the development of an endeavor into a science.

For the largest group, I use the term stone domain, which is the hard-rock equivalent of other material domains, for example metal (most tools), cloth (most fabrics), and wood (most structures) objects. I divide the stone domain into progressively lower ranks of class, family, type, subtype, and variant.

The Stone Domain

The stone domain includes all notable stones, and collections of notable stones, whether modern or ancient, tall or short, piles and walls, towers and turrets.  The term “notable” doesn’t specify a size, composition, or concentration.  Rather, it’s the stone or group of stones on which your attention is focused, meaning that they are differentiated from those in the soil.  Ledge is excluded. 

The domain of stone consists of four classes.  Walls are typified by the classic New England fieldstone wall, and related foundation and mill-dam walls.  They meet the three fundamental criteria of elongation, continuity, and elevation. Rows are typified by the spaced lines of boulders protecting yards from vehicle traffic, as well as the low stones along borders of gardens. Rows satisfy the criterion of elongation, but fail either the criterion of continuity (by having gaps) or the criterion of elevation (by being too low).  Concentrations are a broad group that includes piles and monuments.  Usually they are differentiated from walls because they aren’t elongate enough.  Finally, notable stones are typified by the isolated boulders or quarried slabs so frequently adorning new construction.  Gravestones and grinding stones also qualify as stones, provided they are considered individually.

Each class is subdivided into families that are distinguished by features that can be observed in the field, but which are named more generically based on their purpose or relationship to the soil.  There are seven families within the class walls.  Freestanding walls stand above the ground surface (grade) on both sides, or nearly so.  Here, the focus is principally the segment rather than the enclosure. A classic fieldstone wall is a familiar example.  Flanking walls are embedded into the slope, meaning that one side is intentionally higher than the other.  They stabilize terrain by physically supporting the soil on the upslope end (retaining walls), and (or) by protecting it from erosion. Raising walls are built to raise the ground surface above grade on three or more sides, either with a single continuous curved wall or series of segments.  A raised garden bed is the most familiar example.   Impoundment walls are built to hold back water, rather than soil.   The stonework around a classic mill dam is the most familiar example.  Foundation walls are built to hold up structures, usually wooden buildings such as houses, barns, and sheds.  Many serve a subsidiary purpose as retaining walls.  Confinement walls are small enclosures in which the focus is on the enclosed space, rather than the segment.  The town pound is a familiar example Normally, such walls are un-roofed, though they need not be.  Stone chambers and New England’s rare stone houses fall into this category as well.

There are two families within the class, stone rows:  A solid row is a continuous (not spaced) line of abutting stones too low to be considered a wall.  Typically they are cobbles, which are often painted, and used as a border.  In a spaced row the stones are not abutting. Typically, these are high enough to qualify as a wall but are not continuous. A dashed row has less space between the stones than the stones are wide. A dotted row has stones further apart than their width.

There are three families within the class stone concentrations. Stone surfaces are concentrations of stone that abut one another side to side, but are not stacked. Outdoor patios and walkways and veneers of stone which protect against erosion, are the most common types. Stone uprights are deliberately built concentrations created for a variety of purposes, including monuments (stacks, cairns, and survey markers), pillars (which support objects from below), and chimneys.   Stone piles include a variety of un-stacked mounds and heaps, ranging from the filled corners of many walls to those covering Native American burials.  It also includes ring-shaped piles, which grew up surrounding trees and wooden fence posts.

The class notable stones is divided into three families:  Standing stones   are generally unadorned, elongate in shape (length must be more than three times width/thickness), and their lengths are perpendicular to the ground, or nearly so.   Most were deliberately inserted into this geologically unstable position, but are few are natural. Glacial Erratics are notable and often associated with cultural phenomenon, hence are included in this group.Placed stones are notable stones that don’t meet the requirement of a standing stone (upright) nor are they modified or adorned. (The most common type of placed stone is a glacial erratic that has been moved, either from the surface or an excavation). Modified stones are notable stones that were deliberately prepared and shaped for any cultural purposes.  Generally they are adorned by engraving or other tool marks.  Examples include gristmill stones, weights, large troughs, and cut graveyard stones .  

Class: Stone Walls

Family: Freestanding Walls  

STONE BAND:   The most primitive type of freestanding wall is little more than a low mound – really an elongate pile – of stone that is usually neither straight nor of uniform width, and which, in most cases, accumulated piecemeal beneath a fence line.  This is the most primitive state of stone wall, scarcely qualifying. Typically, its stones are dumped, rather than stacked, though there is a constant variation. Sometimes, the trace of the stone band is highly irregular.  Wavy stone bands result when a straight line wasn’t used to guide the dumping of stone.  Beaded stone bands form when individual piles or dumps of stone occur along a straight line. Sometimes this happened when the stones were selectively thrown below fence posts, rather than rails. 

SINGLE WALL:   The most common type of stone wall is the single wall, sometimes called the “pasture wall” or “farmer’s wall.”  Although often two or more stones wide at the base, the dominant theme is that of a single stack, in which stones are placed one on another, the chief support being along the line of the wall, with no planned support from side to side. Single and double walls are differented at the top, not at the bottom.

The most common subtype is the normal single wall. Typically they are tall triangles in cross section, wider and the base and stacked. The panel subtype is similar to a normal single wall at the base, but above the triangle is single vertical stack supported entirely by the line of the wall. When these panels are well fitted, which is usually the case in slabby rock settings, there is little space between the stones. But where the stones are dominantly rounded, open space is common, hence the term lace wall. A third common type of single wall is the abutting wall. In this case, large stones abut each other. Common variants include the boulder, slab, and pale wall. In the latter, slabs of stone are inserted into the ground like pales that abut.

Informally, there are several distinctive sub-types.   First is the cordwood wall, which is built of prisms of stone laid endwise across the wall, hence they resemble split firewood. These occur only where the bedrock geology produced odd-shaped stones, usually in tightly folded slate country or in hexagonal columns of basalt.  Most evocative is the lace wall, which is especially common on Martha’s Vineyard.  These often wider at the base, lace walls are built of equant, but odd-shaped stones in such a way that the top of the wall resembles lace, meaning that one sees almost as much air as of stone.  Basically, you can see though these walls, especially at the top.  This is also true of the cannonball wall, which a close cousin of the lace wall, though made of unusually rounded, even-sized stones. 

DOUBLE WALL:  The most familiar, respected type of wall is the double wall.  Its diagnostic element is the presence of at least two lines of stone laid or stacked close against one another such that the stones slant inward towards the center, which is often filled with rubble.  It may be capped or uncapped.  There are three basic subtypes of double wall.  The normal double wall is stacked, rather than carefully laid, and usually thigh-high or lower.  Built from both sides, it lacks the architectural or artistic refinement that would qualify it as an ornate wall, which is one of any type where extra effort and expsnse was made.   Most normal double walls are exterior boundary walls for prosperous, but middle class farms.  If capped at all, they are capped with fieldstone, culled for its tabular shape and large size. A hybrid wall is common subtype o double walls in which the main structure of the wall is built as a double wall, but which is capped by a heap or stack of stone, mounded up on the platform below.

An ornate wall need not be ostentatious, though many are. Most were laid, rather than stacked, with architectural and aesthetic concerns, rather than stone disposal or territorialism, being paramount. Being expensive to build, ornate double walls are often called estate walls, especially when they are high and associated with hedges.  The most common variant of the ornate double wall is the capped wall, which is perhaps the most common style around public cemeteries, and identified by quarried stone blocks, usually granite, marble or sandstone, laid on a fieldstone base. Slightly less common is the quarrystone wall, which is built entirely of quarried stone, and therefore, by definition, an ornate wall.  Copestone walls are also common, especially in colonial-era English towns.  They were built by placing the final tier of stones on edge across the double wall, to produce a fence-like top (related to the spikes, hedges, and broken glass) to prevent climbing or sitting on the wall.  Informally, the most ornate of all is the turreted wall, in which pedestals, resembling the turrets on medieval castles, are built into the wall, clearly for show.  Of course, any of these can occur with the others. A final variant of ornate wall is the guard wall, which is ornate by virtue of its height of more than five feet, and usually includes other ornamentation. 

BROAD WALL:   The wall exceeds the width required for structural support in a double wall, which is typically about two and a half feet wide at the base.   Normally a third line of stone is present.  The subtype, disposal wall, is essentially a double wall with an extra-wide middle zone, one that is commonly about ten feet wide, but which may be as much as thirty feet. On each side is a stack of stone laid with the best faces outward.  The center is usually filled with dumped and tossed stones and rubble, with no effort to its arrangement. These are clearly the result of a planned, single, clearing effort, usually a capital improvement on a farm.  Only rarely are disposal walls ornate. Another common subtype of broad wall is the once-again wall, which contains an additional line of stone laid against a previous wall.  Most common is the case of a classic double wall flanked by a heap of stones stacked or tossed on one side.  This is diagnostic of the re-activation of fields, especially orchards, where a renewed effort at capital improvement took place, usually with tractor loaders.   A very distinctive, though rare version of a broad wall is the subtype walking wall, which is essentially a raised sidewalk.  Its diagnostic elements are the presence of both enormous tabular capstones and pedestrian access via a stile or stairway.  Considering the severity of the mud season in much of New England and the frequent trips made between house, barn, and stockyard, walking walls were often worth the effort.

ABUTTING:  The final type of freestanding wall in the abutting wall, created by a continuous line of single stones high enough to qualify.  Most common is the boulder wall, made of boulders simply rolled, then levered into place, touching each other.  Slightly less common is the rock slab wall, built with jagged blocks, rather than boulders, and almost always placed with 20th century  construction  equipment.  Rare, but even more distinctive, is the stone pale wall, built of slabs inserted into the ground like standing stones, but abutting each other. 

Family: Flanking Walls

This family is the second most common type of stone walls.  They flank a slope, usually at a break in slope, rather than stand freely above grade. These walls are built to stabilize a bank either by holding back the earth, by protecting it from erosion; commonly both. 

RETAINING WALL :  The retaining wall type is very common, especially in village, garden, and barnyard settings. It is defined by its asymmetry, b being high on one side and low (usually at grade) on the other. The most common subtype is the below-grade retaining wall, which supports an excavated face cut below grade.  Less common is the above-grade retaining wall, which supports a face backfilled behind the wall to produce a flat space at higher elevation.  Modern retaining walls in gardens and landscaped yards are often curved.  Older ones were usually straight. Designed principally to hold back the earth, the structure of most retaining walls is that of an inverted wedge of stone, thickest at the base, where most of the support is needed. Usually they are laid, rather than tossed, because the extra strength is required.  Usually, extra care is given to drainage at their bases.  This is often accomplished with a heap of rubble tossed on the uphill side.  Most are designed with a battered face leaning uphill, especially when the wall partitions a continuous slope, and the stones are poorly shaped for building.  False-retaining walls were originally built freestanding, but have since collected enough earth on their upslope ends to be indistinguishable from a poorly built retaining wall. 

Well guards area a special subtype of retaining walls. They are the “horseshoe crabs” of the taxonomy, primitive, unique, and yet widespread.  When most primitive the well guard is little more than a low circular or square rim of stones built just above ground level to prevent the washing in of  debris or the entry of animals into the otherwise potable water supply.  In many cases, however, the stone foundation extends well below the ground as a lining for the well, one that might otherwise be called either a facing wall (type of armoring wall) because it served to prevent erosion and a retaining wall because it kept soil from slumping and flowing into the well, especially when the water table rose during snowmelt and runoff.  Sometimes, the stone is arranged in the form of a vertical arch so that that the pressure of the earth directed inward towards the well is supported by the arrangement of stones.

ARMORING : The armoring wall is also a common type of flanking wall.  Here, the goal is to protect the land from erosion, rather than hold back earth, though both functions were often served.  The most common subtype is the rip-rap wall, which is a wedge of stone, usually dumped against the base of a sea cliff, an eroding shore, or a stream bank, wherever floods and coastal storms threatened the land. The other common subtype is the facing wall, built to provide a regular, resistant face against the force of erosion.  There are two common variants of facing walls: the sea wall usually built above a rip-rap wall, and the stream-bank wall, designed to prevent stream side erosion.  A special type of streambank wall is the chute wall, which was essentially the flanks (and often the bottoms) of a chute for controlling water near mills, especially in the tailrace.  Both are designed to prevent erosion from the side.  Mill dams, though built with an even face, are not included in this group.  The stones of their tail-races, often are, however.

Family: Raising Walls

The family of raising walls is designed to create and maintain a ridge or plateau of soil above normal grade, usually on land that is flat, rather than sloping.   It shares similarities with above-grade retaining walls

RAISED LAND :  These were built to raise land above swampy or  marshy soils, or above the water itself.  In most cases, the stone was hauled in and dumped to create a narrow, solid, artificial peninsula on which a range of activities took place. Alternately, the walls were built to support artifical fill , usually to convert marsh; these are called edge-of-fill walls.  Subtypes of peninsula walls include: causeway, to create a transportation corridor across wet ground, usually a marsh; stone groin, built perpendicular to a shoreline to prevent coastal erosion and maintain a beach by trapping sand; stone jetty, a pair of stone walls flanking a navigable tidal channel and designed to prevent sedimentation; and stone pier, designed as a platform for ships to exchange cargo.  These types are defined more by function than by structure.

BRIDGING:  Another common type of raising walls are those built over small streams.  Most common is the subtype Culvert wall, which were usually built on upstream and downstream sides of a central fill of rubble or stone, through which a stone culvert was built.  Primitive culverts were usually created by placing elongate stones parallel to the stream then capping them with a tier of more tabular cross stones.  The difference between a culvert wall and another subtype, the stone Bridge wall, is that the latter is built to span a stream, rather than to convey it though a stone pipe surrounded by fill.

Family: Impoundment Walls   

The family of impoundment walls is designed to hold back water, rather than soil, usually to create a permanent pond for downstream mill works, or, more recently, as flood control measures.  Because stone is porous when stacked, impoundment walls require some sort of impermeable lining, which is usually provided by fine-earth, often muck or silt dredged locally from a marsh or clay bank.  Hence, impoundment walls serve primarily as a retaining wall for artificial fill.  Structurally, they are similar to above-grade retaining walls and to causeway walls, though the stone is present to control water erosion, as much as it is to hold back the impermeable materials creating the impoundment. 

Dike:  These walls were built to protect low ground against a rising flood. These are usually built as a simple retaining wall, backfilled with earth on the side with open water.  They are most often seen around natural meadows, which were cut for hay, and which would otherwise be ruined by a late summer flood. 

Dam:  New England, the stone ruins of old dams are almost as evocative as the tumbled freestanding farm wall.  Built across streams and rivers of various sizes, the old mill dam – many of which have since been restored -- conveys the ambience of colonial and early American village settings,  In such settings, there is usually a variety of stone work  associated with the foundation for the mill building, and the chutes through which the water was directed to flow towards and away from the wheel or turbine.

Pool: A final type of impoundment wall was created in high places to store water for later use, fed by gravity.  They include cisterns, designed to catch rain water, tanks for cattle, and a variety of purposes.  Unlike mill dams, pooling walls are usually raised above the ground on all sides.  They are analogous to raised beds, but raise water instead of soil. 

Family: Foundation Walls

The family of foundation walls was built to support something from below, usually a building, usually on two or more sides.  Their diagnostic feature is that the top course of stones was laid as close to horizontal as possible, in order to support the basal beams and sills.  This usually required some care, hence foundation walls are usually laid, rather than tossed in their construction.  Foundation walls are often cut into the slope on the uphill side, hence, frequently share traits with retaining walls, to which they are closely related. 

Cellar Hole:  The most evocative foundation wall is the cellar hole.  Each is the grave of an abandoned house.  House foundations, even on flat land, were usually excavated at least several feet into the ground in order to create a cellar that could be used to store food under cool, but unfrozen conditions.  After excavation of a hole, the cellar was faced off with stone, laid in courses to a height where the basal timbers would rest.  One end of the cellar foundation was usually built up into a fireplace, most of which were also made of stone, most of which have since collapsed. The weight of the overlying building is what held most cellar foundations in place against the pressure of the creeping soil.  Hence, with the buildings gone, most cellar holes collapsed inward.

Building Foundation:  Most wooden buildings had stone foundations.  By far and away, the most common are the subtype barn foundations, which are recognized by their larger footprints than for houses. On slopes, most building foundations were excavated back into the earth, producing a walk-in half-cellar, which was sometimes large enough to serve as a separate level holding livestock.   In this group are also the foundations of large houses, some of which did not have cellars, and some of which kept going upward to be the walls of stone houses.  These are dubbed house foundations to distinguish them from cellar holes. Another subtype called outbuilding foundations are seldom excavated into the ground; instead, courses of stone were raised on the downhill sides and corners of buildings of various sizes; garages, sheds, cribs, hay stacks and even outhouses. 

Family: Confinement Walls

In the family confinement walls, the focus was not on the wall, but on the space created by short wall segments on three or more sides.  The boundary between a small field with free standing walls and a large pen with confinement walls is, unfortunately,  arbitrary

Stone pens: These are the most common type of confinement walls, generally small, unroofed, enclosures bounded by stone on at least three sides, ranging from about 20 feet to about 100 feet on a side.  All were used to contain animals for some purpose.  The most common subtype is the stone pound, which is essentially a heavy-duty public jail for wayward livestock, almost always located on or near a public road. Most were arranged in such as way as to prevent the escape of even the strongest bulls, the most resolute hogs, and most nimble sheep. Most are no more than fifty  feet on a side, with some as little as twenty.  The walls are either built of massive stones, and/or laid with extra care to ensure durability and structural stability.  Another subtype is the stone corral, which are more general in function, and located anywhere on farms. Large variations of this type are sometimes referred to as stone yards. Sometimes laid and sometimes tossed, corrals served to partition space for feeding, breeding, slaughtering, nursing, and culling, usually in the vicinity of the barn.  The term stone fold is the outbuilding equivalent for the corral, into which sheep were folded for protection. 

Ring Walls:  These are small, unroofed, circular enclosures that are do not qualify as pounds or pens, usually because they are much too low. They are among the most difficult type of confinement wall to classify because there is a continuum in size and form from disintegrating stacks that once surrounded a campfire, to very-well built, vertically walled enclosures more than fifty feet in diameter. Small, poorly built rings grade into piles. The subtype fire-rings are to recognize because the stones are arranged into a circular stack and are distinctly cracked, split, charred, and reddened by the fire’s heat.   Most commonly, they range from 20-40 feet across, and were built to help contain charcoal or potash fires, which needed to burn slowly for days, and therefore required extra care in confinement.  Charcoal was a vital fuel for home heating and colonial manufacturing before the widespread availability of coal, and long before anyone thought forest denudation was a bad thing. A second subtype of ring wall is the stone circle, of which I have seen only several, though several are reported in the literature. Closest to typical freestanding walls are those built to surround a large shade tree, which has since disappeared.  They are principally architectural structures, guides for horse-mills, benches, and decorative borders.

Stone Chambers:  This rare type of walls includes any and all enclosures that were roofed, often with stone.  This is also the most enigmatic group of all because it includes the dozens of stone chambers, alleged to be everything from simple root cellars to meditation huts. In this category are also stone passageways and underground stone-roofed tunnels are rare as well.

Class: Stone Rows

The class stone row contains objects that form a straight line, but are either discontinuous or too low to qualify as a wall.   They are usually decorative borders of some sort.  :

Family: Solid Rows

This family of stone lines must be low and abutting.  Most are made of stones small enough to move by hand, and are almost exclusively used for decorative purposes in parks, gardens, and homes.  The most familiar is the cobblestone or paving stone border along a driveway, separating grass from asphalt, or mulch from yard.  Blocks of cut stone, bricks, and jagged stones are used as well. 

Family: Spaced Rows

A spaced row is discontinuous, meaning the stones do not touch each other.  For a dashed row, the space between the stones must be shorter than their width along the line. For a dotted row, the space must be wider. The informal type, cobble-dots are composed of rounded stones smaller than skull sized.  Boulder dots and rock dots are larger, rounded and jagged versions of dotted lines that are  so common around sand and gravel pits and in developments where excavated stones were kept for use in vehicle access. 

Class: Stone Concentrations

This class includes clusters of stone of any shape that do not qualify as lines or walls, either because they are not elongated or tall enough. The most common types of concenrations are stone piles used to dispose of stone, monuments to mark boundaries, veneers to prevent erosion, and natural concentrations.

Family: Stone Surfaces

This family of stone concentrations are only one stone thick.  Stone pavements are a type that is flat on the ground.  Most common is the tiled pavement, in which the stones are placed flat-side up, to form a usable surface such as a floor when inside, a patio when outside, or walkways, driveways, and corridors.  Also included in this group are cobblestone pavements (cobble for short).  Most cobblestone pavements are natural, rather than created by humans.  They are what geologists call lag horizons, places where the finer materials was washed or swept away. The base of most New England streams and beaches are cobbles. The corners of most pastures are cobbles produced where the extra stomping and grazing of livestock accelerated surface erosion.

In contrast, slope veneers are a type of stone surface that is inclined.  They are similar to armoring walls, but are not upright structures, and therefore do not qualify as walls. The placement of tile, stone, or even a single layer of rubble stone on a sloping surface is a common way of protecting it from erosion, something that is especially common in drains along roadsides.  Some stream embankments and sea walls fall into this specialized, and somewhat unimportant type of stone concentration/

Family Stone Uprights 

This family of uprights includes objects of any size and height that are more than two stones deep or two feet high that fail the elongation criterion.  This group is more complex than stone surfaces because they are three-dimensional, rather than two-dimensional.  Also, all are built, rather than merely dumped.

MONUMENTS: Probably most common type of uprights are the dozens of stone monuments, of varying degrees of sophistication, ranging from elaborate cylindrical columns with turreted towers, to simple stacks of stone on rock slab, built to clear a field.  The most primitive subtype of monument is little more than a simple stack of stones of any height. (Where the stone merely tossed or dumped, rather than stacked, it is not considered an upright.) Survey monuments are common on properties without boundary walls, which are often later subsumed into walls. Stone cairns are a subtype common to outdoor parks and other public lands, where they were used to mark trails.  Many cairns indicate the growth of hiking as a hobby in the 20th century, punctuated by the CCC (Civilian Conservation Corps) movement, and the creation or outdoor clubs such as the Appalachian Mountain Club.    Related to cairns are stone statues, a fast-emerging form of folk art in which stones are placed in such a way as to resemble stick-figures.  Most enigmatic are stone boxes, which would be considered chambers if they were hollow; often they are nothing more than masses of stone arranged in a cubic or rectangular shape too short to qualify as a wall.  Some of these I have seen in old cemeteries near exhumed graves, the rocks merely piled in a tight cubic shape.

PILLARS: Another highly variable type is stone pillars. Cylindrical or square, pillars are like foundations because they were carefully built to support something from below, usually the central beams of large structures such as barns.  Most are tumbled down because their stability derived from the weight of the building they formerly supported.  The most primitive pillar is little more than two stones stacked one upon another.

SPANS:  This type uses stones to create a span that supports weight. Simplest is a pair of two stone uprights and the cross piece that spans them. The most common subtype of this construction  is a stone bench usually built with a flat, blade-shaped stone, spanning a pair of boulders.  In my experience, an equal number are made of quarried stone and field stone. Other spans are clearly decorative, or symbolic.  Stone portals may be either made with lintels or arches .

CHIMNEY:  This is a specialized type of upright, usually found in association with cellar holes or building foundations, or of kilns and forges.  Though usually collapsed, they are diagnosed by the presence of the smoke flue, a square chamber that once conducted the exhaust.  The rocks often retain some of the soot, and reddened scorched zones. 

Family: Stone Piles

This largefamily of stone concentrations is the second most common type of stone in New England, after stone walls. It grades into the most primitive types of all freestanding walls (stone bands) when they fall short of the 4:1 length/width  ratio.  They also grade into uprights when the stone is stacked, rather than merely dumped.   Essentially, a pile is a disordered granular solid composed of particles of stone, usually with a broadly conical or mounded shape resembling a shield volcano.  Sometimes the direction in which the stone was were off-loaded can be inferred from the shape of the pile and the fraction of large vs. small stones.  If there is a change from large to small stones across the pile, the side with the small stones is usually the one that was furthest away.

FREESTANDING:  This type of pile is not connected to either a stone wall (attached type) or to a boulder or rock slab (surmounting type). The subtype mound a disordered heap that rises above grade. They are especially in primitive areas, or those farmed for just a generation or less. An unusual variant is a burial mound , often associated with Native American burials.They are usually elongate with the central stones collapsed downward with an imbricate pattern..An infill pile  is a subtype associated with low ground filled with stone rubble, often to help to bring it up to grade or to provide a crossing surface.  This is common in swamps and across marshy streams.

Ring piles are   These are circular, rather than continuous . A tree ring pile is fairly common, though it often goes undetected because they are so low to the ground.  On primitive farmsteads, the largest stumps, especially of sprouting trees like chestnut, were often left because they weren’t worth the trouble of grubbing out.  Refuse stone accumulated on and adjacent to them. When the stumps finally rotted, the pile of stones developed a stone free center, resembling a large donut.  Though the largest of these could qualify as ring walls (because the stones rest above one another, they are more properly classified as piles (albeit with hollow centers), though the intent was to use, rather than dispose of stone.  Many campfires are banked by rows or low stacks stones, which would normally qualify them as stone rows or stone walls.  However, all but the most recent have usually collapsed into a zone, one-stone thick, producing a ring-shaped veneer of stones, best classified as a specialized pile. Many campfire rings have since been abandoned, and occur either as archaeological sites, whether as encampments for militia, or solitary fires for prehistoric activity.   Related to a tree ring, but at a smaller scale, is a stone rosette.  These developed not around trees, but around fence posts, which often benefited from the few stones leaned up against it.   Most such stones came form the hole holding the post, so there was no hauling involved.   The hollow center of a stone rosette is scarcely detectable, but the stones are still there, arranged as if petals on a flower, radiating out from what used to be the base of a fencepost.

ATTACHED: This type is attached to a stone wall.  Most distinctive of all subtypes is the corner pile, where stones are dumped by the cartload into what was formerly bounded by a wall.  Usually this represents the conversion of the field to mechanized farming, when small stones, previously no problem, began to get caught up in the machinery, precipitating their removal.  Similar deposits can also be present anywhere along a wall as the subtype of flanking pile.  In some places, flanking piles grow high enough to spill over the old wall, often burying it completely.  The subtype topping pile lie directly on double or broad walls.      The presence of attached piles, especially flanking and topping piles, proclaims that stone disposal was much more important than aesthetic considerations.

SURMOUNTING: This type occurs where the pile of stone is associated neither with a wall or the ground, but on a notable slab of rock that apparently was too large to move.  It signifies a greater interest in stone clearing than in wall building; otherwise the stone would have been used as a resource.  Surmounting piles grow until they submerge the slab, at which point they resemble free-standing mound piles.  The significance of this is to explain why an otherwise impeccably cleared field has a pile in the middle of it. 

Class: Notable Stones

This class includes those objects in which a single isolated stone, rather than group of stones (walls, lines, concentrations) is the object of attention.

Family: Standing Stones

This family of notable stones must be large, elongate (prisms, columns, or blades), and oriented such that their center of gravity is high off the ground.  Most were inserted into excavated holes and propped up in order to stand straight.  The most common type are stone posts.  Most are easily recognized because they were unambiguously quarried from granite, equipped with iron hardware or drill holes and are members of a group; most often a pair marking a gate.   In contrast, stone obelisks are elongate stones that are too oddly shaped to be considered a post, most of which were tooled into prismatic shapes and used as property markers or grave sites.  Obelisks differ from monuments in being solitary, rather than a collection of stones.

Family: Glacial Erratic

Unquestionably, large glacial erratics are notable stones. Though not placed by humans, they are notable and often associated with cultural phenomenon, such as monuments or meeting places. They are not the only componets of the stone domain not emplaced by humans: for many veneers are also natural.  This family must be  used when a human movement cannot be proven, even if it is suspected. Most were let down by the ice during the final stage of melting. When human movement can be proven, but there is no modification to the stone other than scraping,

Family: Placed Stone

When any enormous stone is moved, either to move it aside or to use it for architectural ornament, it becomes what I call a placed stone. Most are modern and associated with decorative plantings. 

Family: Modified Stone

A third family  is the modified stone, brought to their present appearance, by anything that was deliberately engraved or carefully shaped (beyond hammer blows), including statues, plaques, grave markers, grinding stones,  and other architectural ornaments made of stone.   Typically, an old grinding stone or some statue is set out for display. 

Describing Walls

No taxonomy is ever complete; other wise it would include as many categories as objects.  There is always a need to describe individual objects at a finer level than the subdivision allows. Consider the case of the classic double wall, which is a subtype (classic) within  a type (double), within the family (freestanding), within a class (wall).  It could be mortared, or un-mortared, built of fieldstone or quarrystone, or be capped or uncapped.  To encompass all of these common features in a single taxonomy would require a minimum of eight different variants.  Normally, it is preferable simply to have one category (in this case the subtype classic double wall) then describe it as needed. 

I suggest the following order in describing stone walls.

• Condition (damaged or undamaged etc.)
• Degree of order (stacked, dumped, or laid, etc.)
• Stone topography (boulder, slab, chunky
• Stone source (fieldstone vs. quarrystone)
• Structure (single vs. double, etc.)
• Function (foundation, retaining, etc.)

 For example, the wall I see most often, just east of my house is a  partially collapsed, crudely stacked, slabby, fieldstone, classic double wall.