Big Sky Geophysics is a consulting and contracting company located in Bozeman, Montana. I operate the company as a sole proprietor. I have been working as a geophysicist for over twenty years and both execute field work and perform survey planning, processing, and interpretation. I have worked throughout North and Central America and in Africa on projects ranging is scope from one day engineering surveys to multiyear follow ups of airborne surveys. I use potential field (gravity and magnetics), electrical/EM, seismic and radiometric methods for applications in mineral exploration, hydrocarbon exploration, and engineering studies.

I believe in using the best equipment possible for collecting, processing, and interpreting geophysical data. I use a large variety of computer programs including:

Geosoft Oasis Montaj potential field mapping and processing software
EMIT Maxwell EM processing and modeling software
Geotomo's resistivity/induced polarization modeling and smooth model inversion software based upon the code of Loke
Allen Cogbill's gravity terrain correction software
Encom Technology's ModelVision gravity and magnetic modeling software using prisms
NGA GM-SYS gravity and magnetic modeling software using prisms
UBC's GRAV3D and MAG3D 3D smooth model inversion software for gravity and magnetic data
Kansas Geological Survey MASW (surface wave) and seismic refraction processing software
SU seismic/ground penetrating radar reflection processing software
ArcView GIS software
Golden Software's Didger digitizing program and Voxler 3D rendering program
Numerous public domain, commercial, and personal programs written in FORTRAN, C, and BASIC for formatting and processing various geophysical data types.

I am gradually acquiring all of the field gear necessary to perform surveys. At the present time I own:

Potential Fields:
LaCoste and Romberg G model gravimeter with electrostatic readout
Trimble 5700 survey grade (centimeter level accuracy) GPS base/rover pair with RTK and post processing options
GEM GSM-19W Overhauser walking magnetometer/gradiometer
GEM GSM-19TG proton precession walking magnetometer/gradiometer
Time Domain resistivity/induced polarization (IP)
EMIT SMARTem24 multifunction receiver (8 channel, 24 bit A/D)
Walcer KW10 10 kVA time domain transmitter
Walcer MG-12A 12 kW 400 Hz motor generator
Iris Instruments VIP3000 3 kVA transmitter
Honda 5 kW 60 Hz motor generator
Time Domain Electromagnetics (EM)
EMIT SMARTem24 multifunction receiver (8 channel, 24 bit A/D) with transmitter controller
Crone Geophysics 30A transmitter system and Crone receiver coil
Trimble ProXRT (sub meter accuracy) GPS receiver
Frequency Domain EM
Apex Parametrics Max-Min II+ EM induction system (222, 444, 888, 1777, 3555 Hz) with digital storage
Apex Parametrics Max-Min II EM induction system (222, 444, 888, 1777, 3555 Hz, analogue)
Geonics VLF receiver (approximately 20 kHz range) with resistivity option
Mala Geoscience Easy Locator 450 MHz ground penetrating radar
Geometrics 48 channel seismic system (2 24 channel Geodes, 24 bit A/D)
4.5 Hz, 8 Hz, and 100 Hz geophones for MASW, refraction and reflection surveys
16 lb. sledge hammer source
Bison AWGIII 550 lb. accelerated weight drop mounted on trailer
Geofyzika GS-512 gamma ray spectrometer (modern with digital storage) with large (3") external crystal
Exploranium GR110 gamma ray scintillometer

If you feel I may be able to help you with a project, please contact me. I enjoy both field work and processing/interpretations and will work to incorporate any geophysical planning and results with additional data such as geologic mapping and well logs, geochemical sampling, and existing water table information. If you wish to have additional information about my experience and education, I have provided my resume. I am pretty fluent in Russian and German and speak some Spanish. I encourage you to consult the case studies. I also discuss some of the advantages and potential pitfalls of using GPS positioning systems with geophysical surveys.

Clark Jorgensen
P.O. Box 353
Bozeman, Montana 59771
+1 (406) 587-6330 telephone/facsimile
+1 (406) 580-9718 mobile