Stratigraphy and paleomagnetism of the Esja, Eyrarfjall and Akrafjall mountains, SW- Iceland.

Detailed geological and magnetic mapping in an area of Pliocene and Plio-Pleistocene volcanic rocks in SW Iceland has enabled us to correlate a 2 100-m-thick lava succession with similar dated sequences in Iceland and with the ocean-floor geomagnetic polarity time scale. This correlation, supported by additional K-Ar dating, implies 1) that the succession is between 4.2 and 1.8 Ma in age, 2) that at least 13 glaciations occurred in W and SW Iceland between 3.1 and 1.8 Ma ago, and 3) that at least two geomagnetic events are present in the Lower Matuyama epoch. Paleomagnetic results from 353 igneous units, mostly basalt lavas, are tabulated. Analysis of directions from 258 of these shows them to posses some serial correlation; their mean is very close to a central axial dipole field value, but explanations are proposed for observed systematic departures from this field in other Icelandic paleomagnetic survey results.-Authors