Geostuff

Around 1990, there was a double evolution in seismic surveys. Petroleum exploration crews had started using what are called `distributed systems` as the number of channels used became too great for the use of conventional geophone cables. Instruments for seismic exploration: cableless seismographs, borehole geophones, land streamers, rollalong switches. At about the same time, the instruments used for shallow seismic surveys had developed capability sufficient for conducting reflection surveys, though on a much smaller scale. Besides the instrument, shallow reflection surveys needed the ability to `rollalong`, which required a `rollalong switch`. The used ones previously available from the oil and gas surveys were generally quite large and worn out.