This English language special issue of Zeitschrift für Geomorphologie
(Annals of Geomorphology, special volume 132) contains 10 papers that
were originally given at the Inter-national Workshop Geophysical
Techniques in Geomorph-ology in February 2002. Periglacial (or
paraglacial, the term used in this volume) environment is the
geomorphic setting discussed or, more specifically, areas near
glaciers with the resulting permafrost and associated sedimentary
systems. The purpose of the volume as stated in the preface is to
bridge the gap between geophysics and geomorphology and to encourage a
closer cooperation between researchers in both disciplines. This
special issue has been very suc-cessful in showing how geophysical
methods and geomor-phology can be combined to produce meaningful
results in understanding the shallow structure, especially the depth
and distribution of permafrost. This book s strength lies not in the
details of the geophysical theory, but in the discus-sion of how the
particular glacial environment affects sur-vey planning,
implementation, and interpretation.
I will briefly discuss all chapters, since each contains a great deal
of material directly relevant to the field application of the
method(s) being discussed, and all deserve attention. The first paper
is a theoretical discussion of a glacial sediment system by
C.K. Ballantyne; the remaining nine reports are case histories. They
are divided by method: three on dc resistivity, two on seismic
refraction, one on GPR, and one on RMT (radiomagnetotellurics). The
last two chapters discuss an assortment of techniques. The physical
property making possible the application of these geophysical meth-ods
to permafrost studies is the dramatic change in resis-tivity and
seismic velocity that occurs when water and earth materials freeze.
In the second chapter (B. Etzelmüller and others) 10 different
geomorphologic sites are examined with the one-dimensional
dc-resistivity method. Investigating the application of this method to
regions that lack geomorphic permafrost indicators, the authors
concluded that the resis-tivity method could not be exclusively used
but must be employed with other techniques. C. Kneisel in the
follow-ing chapter reaches the same finding and emphasizes the
importance of using two-dimensional resistivity surveys, GPR, and
seismic refraction in addition to knowledge of the geomorphic and
geologic situation. In a digression from these studies in both scale
(only a few meters) and application, O. Sass shows how 2D-resistivity
methods can be used to determine the wetness of the near surface of
out-crop faces. This method could also be applied to archeological
studies.
T. Hoffmann and L. Schrott evaluate the intercept-time method and
three other schemes used to interpret seismic refraction data and
conclude that more than one approach may be required.
S. Hecht, using seismic refraction, describes shallow sub-surface
investigations in unconsolidated sediments. He finds that, despite the
hidden layer problem, detecting lateral velocity variations are a
strong point of this method and par-allel seismic refraction lines
were used to illustrate the three-dimensional sediment bedrock
interfaces.
Application and limitations of GPR to a region of rock glaciers on
Svalbard is discussed by I. Berthling and others. They propose that
the 25 or 50 MHz frequencies should be 000 THE LEADING EDGE SEPTEMBER
2004 SEPTEMBER 2004 THE LEADING EDGE 935used, with the former being
more difficult to field deploy. Like the other papers in this volume,
the authors give detailed advice for the application of the method
they are discussing and provide the trade names of the equipment and
data interpretation software packages they use. This gives the volume
the sense of a field manual.
RMT was used in three investigations by A. Hördt and G. Zacher: the
margins of an industrial waste site; aquifer thickness in a
groundwater survey (together with seismic refraction); and an
agricultural area. The last of these inves-tigations involved
searching for shallow cavities. The authors conclude that RMT can be
better than dc-resistivity, particularly in rugged terrain where
logistics are difficult. They urge the further application of this
somewhat neglected approach.
Several methods are discussed in the last two papers. After reviewing
dc vertical electrical sounding, resistivity tomography, capacitive
coupled resistivity (OhmMapper), electromagnetic coupling (EM-31) and
seismic refraction tomography, C. Kneisela and C. Hauck propose that
dc resistivity tomography is the preferred single method for alpine
permafrost investigations, but recommend that at least one other
technique be used to avoid ambiguities.
The longest and concluding chapter (Evaluation of Geophysical
Techniques for Application in Mountain Permafrost Studies by Hauck and
Mühll) is a comprehen-sive review of nearly all the procedures in the
previous chapters, but also includes frequency- and time-domain
electromagnetic, and details of bottom temperature studies. All
methods are described in tabular form with the first listing
applications (with extensive literature referencing), survey
personnel requirements, and comments and the second comparing their
utility to specific permafrost investigations. These are followed with
an explicit discussion of the advan-tages and disadvantages of each
with reference to a particular permafrost parameter (e.g., detection,
lateral and vertical extent, active layer, and monitoring). Hauck and
Mühll rec-ommend the prevailing view of this volume that a
combi-nation of dc resistivity and refraction seismic tomography
offers the preferred combination of geophysical tools.
While the authors frequently reference SEG publica-tions, most
citations are to non-North American journals in the fields of
geophysics, geomorphology, and permafrost. This provides the
non-European researcher an opportunity to become acquainted with
unfamiliar material. A point of interest is the significant
differences between the Arctic and mountain permafrost both in respect
to geomorphology and apparent resistivities. The book also includes a
CD-Rom with a demonstration version of Sandmeier s refraction seismic
Demo Reflex W, version 3, together with supporting documents.
I recommend this volume to those working in shallow geophysical
studies, but I believe that it is a must for those working in the
field of permafrost investigations. Someday astronauts conducting
permafrost exploration on the surface of Mars will use these methods.
PATRICK TAYLOR Greenbelt, Maryland, U.S. 936
THE LEADING EDGE SEPTEMBER 2004, vol. 23 no. 9