A reconnaissance shallow seismic reflection/refraction investigation in and around the city of Galena, Alaska suggests that Tertiary and/or Cretaceous bedrock, and possible coalbeds within the Cretaceous, is at least as deep as 550 feet in the immediate vicinity of town. Rock could be deeper than 1000 feet under alternate interpretations. Reflections recorded in these data are believed to be from the sediment/bedrock interface. Analysis of these reflections and associated refractions indicates that this interface, interpreted at most of the six profile locations, has a high seismic velocity, possibly indicating non-sedimentary rock (e.g. volcanic or igneous).
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USGS Numbered Series
Reconnaissance shallow seismic investigation of depth-to-bedrock and possible methane-bearing coalbeds, Galena, Alaska