Current surface seismic reflection techniques based on the common‐midpoint (CMP) reflection stacking method cannot be readily used to image small objects in the first few meters of a weathered layer. We discuss a seismic imaging method to detect such objects; it uses the first‐arrival (guided) wave, scattered by shallow heterogeneities and converted into scattered Rayleigh waves. These guided waves and Rayleigh waves are dominant in the shallow weathered layer and therefore might be suitable for shallow object imaging. We applied this method to a field data set and found that we could certainly image meter‐size objects up to about 3 m off to the side of a survey line consisting of vertical geophones. There are indications that cross‐line horizontal geophone data could be used to identify shallow objects up to 10 m offline in the same region.

The common‐depth‐point (CDP) seismic‐reflection method was used to delineate subsurface structure in a 3-m thick, 220-m deep coal zone in the Palau area of Coahuila, Mexico. An extensive series of walkaway‐noise tests was performed to optimize recording parameters and equipment. Reflection events can be interpreted from depths of approximately 100 to 300 m on CDP stacked seismic sections. The seismic data allow accurate identification of the horizontal location of the structure responsible for a drill‐discovered 3-m difference in coal‐zone depth between boreholes 150 m apart. The reflection method can discriminate folding with wavelengths in excess of 20 m and faulting with offset greater than 2 m at this site.

Magnetic surveys and electromagnetic conductivity surveys were conducted at several sites during the course of field work at the Richland/Chambers Reservoir in north-central Texas between 1982 and 1985. Much of this work was conducted at the Bird Point Island site (41FT201), which was used as a proving ground to test the effectiveness of various remote-sensing techniques. Two devices, a Geometrics proton precession magnetometer and a Geonics Limited EM-38 electromagnetic conductivity sensor were tested. The data produced by the EM-38, although initially successful for locating large archaeological features, were less useful for site interpretation than those yielded by the magnetometer.Replicative experiments were conducted to test hypotheses related to feature function and to identify the sources of magnetism present in features. After an experimental hearth and a pit were created on an off-site area, a magnetic survey was conducted and the results were compared with the magnetic responses obtained from archaeological features. Remarkably similar magnetic responses were observed between the experimental features and certain classes of prehistoric archaeological features. Five-cracked rock, consisting of small fragments of iron-enriched sandstone and ironstone, was identified as the primary source of magnetism.In addition to identifying locations of features, the magnetic data also provided information regarding whether or not features had been subjected to multiple episodes of disturbance and reuse. Episodes of recurrent use were indicated by irregular symmetry and unusual magnetic polarity. Several large pit features, which archaeological evidence indicated had been reused, exhibited anomalies with multiple peaks of strong magnetic highs surrounded in several directions by peaks of weak to moderate magnetic lows. In contrast, hearths and pits lacking archaeological evidence of major disturbance or reuse were associated with anomalies that exhibited the normal dipolar signature associated with cultural features—a strong magnetic high with a strong magnetic low immediately to the north. The results of this study demonstrate that the magnetometer has a great potential for aiding in the interpretation of archaeological features in addition to its traditional use as a tool for identifying feature locations.

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