Mapping Depth to Bedrock on a Glaciated Landscape with Ground‐Penetrating Radar

Abstract

In many upland areas on glaciated landscapes, it is difficult to examine soil profiles and determine the depth to bedrock. Glacial rock fragments and irregular or weathered bedrock surfaces limit the effectiveness of auger techniques. While general trends can be inferred from the landscape, depth to bedrock or thickness of till cannot be accurately predicted from landscape position alone. Therefore, ground‐penetrating radar (GPR) was used to map the depth to bedrock for two study sites in Maine. Data were used to (i) determine the variability of the depth to bedrock in similar delineated areas of a map unit, (ii) compare the accuracy of GPR with auger methods, and (iii) evaluate the performance of GPR on a glaciated landscape in Maine. Results were confirmed by studying a trench excavated to bedrock. These results indicated that GPR techniques were more reliable and effective than conventional auger techniques for determining the depth to bedrock, and thus for determining the composition of map units that are based on soil‐depth criteria. Additionally, the screw auger was shown to be an unreliable tool for determining soil depths in moderately coarse‐textured tills having large amounts of coarse fragments.

Methods of surveying the thickness of humous horizons using ground penetrating radar (GPR): an example from the Garmisch-Partenkirchen area of the Northern Alps

“…Its use for pedological purposes, however, is still limited to comparatively few studies, mainly focussing on geoarcheological (e.g., Doolittle and Bellantoni 2010;Leopold et al 2010) and hydropedological questions (e.g., Doolittle et al 2006;Lowry et al 2009;Steelman and Endres 2009;Weihermüller et al 2007). Evaluations of specific diagnostic characteristics of mineral subsoils (Collins and Doolittle 1987;Collins et al 1989;Doolittle and Asmussen 1992;Doolittle and Collins 1995;Doolittle et al 2007;Truman et al 1988;Ziekur 2000) or root systems (Barton and Montagu 2004;Butnor et al 2001Butnor et al , 2003Cox et al 2005;Stover et al 2007) for pedoecological purposes, however, are rather rare. There exists a broad variety of studies concerning characterization and depth estimation of peat bogs and underlying sediments in northern and mid-latitude countries (Bjelm 1980;Hänninen 1992;Holden 2006;Holden et al 2002;Lapen et al 1996;Leopold and Völkel 2003;Lowry et al 2009;Rosa et al 2009;Ulriksen 1981;Völkel et al 2001;Warner et al 1990).…”

Applicability of ground‐penetrating radar as a tool for nondestructive soil‐depth mapping on Pleistocene periglacial slope deposits

“…1 dm, has been described by some authors (Collins et al, 1989;Rebertus et al, 1989;Inmannet al, 2002;Doolittle and Collins, 2004). Doolittle and Collins (2004) stated that most studies with GPR in soil science are done in soils with favorable conditions.…”

“…Geophysical methods, on the other hand, can provide nondestructive and a relatively quick method to investigate natural substrates. Ground-penetration radar (GPR) was used on glacial landscapes to map soil depth even with better results than with conventional drilling techniques (Collins et al, 1989). In the present paper, we describe the use of GPR to map soil depth as well as the structure and distribution of Pleistocene periglacial soil deposits (PPSD).…”

Geophysical Investigations of Soil–Landscape Architecture and Its Impacts on Subsurface Flow

“…Hubbard et al (2005) and Rubin and Hubbard (2006) have summarized the use of GPR to estimate water content, hydraulic conductivity, geochemistry, and lithofacies zonation. Ground-penetrating radar has been used extensively to chart bedrock depths (Collins et al, 1989;Davis and Annan, 1989), changes in rock type (Davis and Annan, 1989), fractures, joints, bedding, and cleavage planes (Nascimento da Silva et al, 2004;Pipan et al, 2000;Porsani et al, 2005;Theune et al, 2006), and faults (Demanet et al, 2001). Bedrock restricts, redirects, and concentrates the infiltration of water.…”