In 2023, the book Archaeology Without Digging, by Deborah Surabian, Nick Bellantoni and James Doolittle,
was published. This book narrates the stories of 10 GPR studies at Connecticut historical sites spanning the
17th to the 20th centuries. While informative, it is somewhat technical in nature; hence this Glossary has
been developed.
Note: In the book a small handful of itmes were encountered which require clarifications. You can access
these directly by clicking Clarify.
(source: AWD book, page 2) Ground Penetrating Radar. A time-scaled system that measures the time taken for pulses of electrmagnetic energy to travel from an antenna to an interface (object) and back. To convert this travel time into a depth scale, either the depth to an identifiable object or the propagation velocity of the electromagnetic pulses through the subsurface must be known.
(source: GSSI website:
https://www.geophysical.com/whatisgpr/.
Scroll down to "GPR Method" section.
GPR works by sending a tiny pulse of energy into a material and recording the strength and the time required for the return of any reflected signal. A series of pulses over a single area make up what is called a scan. Reflections are produced whenever the energy pulse enters into a material with different electrical conduction properties or dielectric permittivity from the material it left. The strength, or amplitude, of the reflection is determined by the contrast in the dielectric constants and conductivities of the two materials. This means that a pulse which moves from dry sand (dielectric of 5) to wet sand (dielectric of 30) will produce a very strong reflection, while moving from dry sand (5) to limestone (7) will produce a relatively weak reflection.
While some of the GPR energy pulse is reflected back to the antenna, energy also keeps traveling through the material until it either dissipates (attenuates) or the GPR control unit has closed its time window.
(AWD book page 11.) What the heck is this? Click Clarify for information on it. Relating to or arising from the action of the wind. Maximum extent of vibrations / oscillations measured from the position of equilibrium. Relating to an area of land Reduce the amplitude of a signal, electrical current, or other oscillation. Dielectric soil moisture sensors determine the soil moisture by measuring the dielectric constant of the soil, an electrical property that is highly dependent on the moisture content. The constant for a dry soil is between 3 and 5; about one for air; and is about 80 for water. Relative dielectric or dielectric constant, is the ratio of the permittivity of a substance to that of free space (vacuum). Values range from 1 for air to 78-88 for water. The process by which material suspended in water is removed from one layer of soil to another by the action of rainfall or chemical decomposition. Fibric materials are defined as those having ¾ or more identifiable plant remains after rubbing. Consist of boulders, gravel, sand, silt and clay from ice sheets or glaciers. They are transported, sorted and deposited by streams of water. The deposits are formed beside, below or downstream from the ice. Sediments deposited into lakes that have come from glaciers are called glaciolacustrine deposits. Composed of coarse-grained bedload and suspended fine-grained material transported by meltwater flowing into lakes bordering the glacier. Whereas glaciofluvial deposits are formed by meltwater streams, glaciolacustrine sediments accumulate at the margins and bottoms of glacial lakes and ponds. Gleying occurs in waterlogged, anaerobic conditions when iron compounds are reduced and either removed from the soil, or segregated out as mottles or concretions in the soil. Marshy wetlands often contain gleyed soils..
(Fig. 1.7) https://www.fosa-ct.org/AWD/GPR_Soil_Suitability_Map_of_CT.png Geophysical Survey Systems, Inc. of Nashua, NH website: https://www.geophysical.com Hemic soil materials are an intermediate between sapric and fibric, and are identified by meeting neither the sapric or. fibric criteria.
(name is generic as used here) One of a large number of soil types cataloged by the USDA. Information on each can be found by placing this template URL into your browser and then replacing the "H" with the first letter of the Soil Series name, and then "Hooksan" by the full Series name. The template URL is:
Unit of electrical resistance, expressing the resistance in a circuit transmitting a current of 1 ampere when subjected to a potential difference of 1 volt. Shorthand for Oscilloscope. Pertaining to processes that add, transfer, transform or remove soil constituents. A scientist who studies origins, composition and distribution of soils and the materials from which soils are formed. Windows-bssed post-processing system developed by GSSI. Refers to both the size of the smallest object that can be detected and the ability to differentiate between 2 closely-spaced features. Sapric materials are the most decomposed and are defined as having less than 1/6 of the total organic content identifiable as plant fiber after rubbing with ones fingers. A siemens is a unit of electric conductance equal to the conductance between two points of a conductor having a resistance of 1 watt. (Its archaic name was "mho",(which is "ohm" -- a unit of electrical resistance -- spelled backwards.)" Subsurface Interface Radar, GSSI uses SIR 3000 and SIR 4000.
To access the SIR-3000 User's Manual please click
https://www.geophysical.com/wp-content/uploads/2017/10/GSSI-SIR-3000-Manual.pdf.
To access the SIR-4000 User's Manual, please click
https://www.geophysical.com/wp-content/uploads/2017/10/GSSI-SIR-4000-Manual.pdf
Note that there also videos and training sessions for both devices, and others, available on the web. The soil is the topmost layer of the earth's crust mainly composed of organic minerals and rock particles that support life. A soil profile is a vertical cross-section of the soil, made of layers running parallel to the surface. These layers are known as soil horizons. A layer of soil, approximately parallel to the surface, having distinct characteristics produced by soil-forming processes. The "Master" Horizon letters below are symbols that designate major breaks in the soil and are base symbols to which other characters may be added to describe the soil in more detail. Three kinds of symbols are used in various combinations to designate soil horizons and layers: CAPITAL LETTER, lower-case letters, and Arabic numerals (1,2,3. . .).
> Master Horizons and Layers:
O,A,E,B,C and R are symbols that designate major breaks in the soil and are base symbols to which other characters may be added to describe the soil in more detail.
> Subordinate Distinctions:
Lower-case letters are used as suffixes to designate specific kinds of master horizons and layers: Ap, plowed A horizon Bh, B horizon with an accumulation of organic matter, etc. For complete lists of these, see the Master Horizon sections below
> Vertical Subdivision: Two or more horizons or layers designated by a single combination of letters which needs to be subdivided.
> Arabic numerals are used, and generally follow all letters. Within a C-Layer, for example,successive C-layers should be designated as C1, C2, C3, etc.
A layer in the soil deposited by geologic forces (e.g., wind, water, ice) and not related to a soil-forming process. O Horizons are layers dominated by organic matter.
> Greater than 20-30% organic matter by weight
> Dark, nearly black or black, color (note: colors can be misleading and should only be used when other field criteria are observed).
> Weak strength, greasy feel, light weight when dry, high fiber content.
> Typically a surface horizon; if buried, often indicates disturbance.
Subordinate Designations
> Oi - Slightly decomposed organic material: fibric
> Oe - Organic material of intermediate decomposition: hemic
> Oa - Highly decomposed organic material: sapric The A Horizon is commonly referred to as the topsoil, and typically ranges from 8-20 cm in thickness. It is a mineral horizon that formed at the surface or below an O-horizon, and is characterized by an accumulation of humified organic matter intimately mixed with the mineral fraction.
Subordinate Designations
> Ap - Plowing or other disturbance. This symbol is used to indicate disturbance of the surface layer by cultivation
The E-Horizon is a mineral horizon in the upper part of the soil, typically underlying an O or an A-horizon.
> It is a light-colored, leached horizon often associated with woodland areas.
> E-horizons range from not being present in the soil to thicknesses of about 10-20 cm.
Subordinate Designations
> Eg - strong gleying, indicating prolonged periods of saturation.
The B Horizon is commonly referred to as subsoil.
> Zone of accumulation within the soil.
> Well-drained soils typically have bright orange-brown or red colors which fade with depth.
> Accumulation of iron, clay, organic matter.
> Horizon generally extends about 45 to 90 cm below the soil surface.
Subordinate Designations
> Bw - Development of color and/or structure. This symbol is very common in New England.
> Bhs or Bs - Illuvial accumulation of sesquioxides and organic matter.
> Bt- Illuvial accumulation of clay, often forming coatings on ped faces, in pores, or on bridges between sand-sized grains.
> Bg- strong gleying, indicating prolonged periods of saturation. C-layers are commonly referred to as the substratum. They are layers, excluding bedrock, that are little affected by soil forming processes. They are unweathered geologic materials.
Field Criteria:
> Little affected by soil forming factors.
> Lack of profile development.
> Lack color development.
Subordinate Designations
> Cd- dense, unconsolidated sediment.
> Cr - weathered or softbedrock.
> Cg - strong gleying, indicating prolonged periods of saturation. R-layers are hard bedrock (ledge)
Cannot be excavated with a backhoe unless fractured. Blasting is often needed to remove this material.
> May be difficult to differentiate from the overlaying soil material and boulders and depth to bedrock.
Subordinate Designations
(none) . Soil Profile: A vertical section of the soil extending through all its horizons and into the parent material. The solum (plural, sola) in soil science consists of the surface and subsoil layers that have undergone same soil forming conditions. The base of the solum is the relatively unweathered parent material.
Solum and soils are not synonymous. Some soils include layers that are not affected by soil formation. These layers are not part of the solum. Soil Survey Geographic database. Accessible at:
https://www.nrcs.usda.gov/resources/data-and-reports/soil-survey-geographic-database-ssurgo. Relating to time. Poorly sorted, unstratified drift that was deposited on, within, or beneath glacial ice. Used to adjust vertically the position of the entire radar profile by moving the Time Zero Position of the ground wave to the top of the profile.Provides more accurate depth calculations by adjusting the top of the radar scan to a close approximation of the ground surface. Position of the first positive peak in a GPR image.
Clarifications
On page 11:. The equation at the top of the page: ≥ 4 dS m-1 at 25o C
looked wrong. On inquiring, it turned out that it looked wrong because the dS m-1 part should have been
expressed as dS/m.
OK. Great. Now what does that mean??
In designing the GPR Soil Suitability Maps, from which the "GPR Soil Suitability Map of CT "
(Fig. 1.7 : page 12) was derived, the designers wanted to recognize the effects of soluble salts on GPR's
effectiveness and depth penetration. In the Soil Surey, they recognize and map soils with an electrical
conductivity of a saturated paste extract, per laboratory analysis and correted to 25 degrees C, of greater
than or equal 4 deciSiemens per meter (ref. the equation), as belonging to saline soils
generally unsuitable for the use of GPR. Though ultimately, their relative suitability will depend on the
concentration of souble salts as well as other soil factors.
And a "Siemen" is...??
Per the Glossary entry above, "Siemens is a unit of electric conductance equal to the conductance between
two points of a conductor having a resistance of 1 watt. Its archaic name was "mho" (which is "ohm" -- a unit
of electrical resistance -- spelled backwards.)"
On pages 19-20: The sentence, "...the British resumed the battle with their remaining two warships..."
was confusing because the previous text stated that the British started out with 4 warships and 1 of them
was disabled ... so why not resume with 3 instead of 2 remaining? The reason is that 1 of the remaining 3
ships, the HMS Terror was what was called a bomb ship, a standoff vessle intended for heavy mortar
bombardments and not shore assaults; hence the 2 vessels.
Note: The Terror in this engagement is the same Terror that participated in the
bombardment of Fort McHenry during the War of 1812 ("...the bombs bursting in air..."); and which was famously lost in
1848 in the disastrous Franklin Northwest Passage expedition.
On page 63:. "British Captain Coote decided to ... run the gauntlet of American rif(l)e and cannon
fire..." It's unlikely that the Americans were using rifles; they were more likely to still be
using muskets. The former use a barrel with spiral grooves (rifling) to increase accuracy at longer range; but
the guns mostly used in the War of 1812 were unrifled muskets, be they the Springfield Model 1795 musket or
the British Brown Bess musket.
Page 76: Second Lieutenant Eugene Bradley and First Lieutenant Frank Mears
"were strapped into the cockpits of their Curtis P-40s..." The manufacturer of the P-40 was
Curtiss, not Curtis. (Admittedly a small oversight to some, but...)
On page 77 (bottom): "Among the groups helping in the Bradley work was 'Friends
of the Connecticut State Archaeologist." It should have read, of course, 'Friends of the
Office of State Archaeology'." (Not so small an oversight.)