A 2330-m-thick sequence of basaltic lava flows near Neskaupstadur, eastern Iceland, yields K-Ar ages ranging from 11.8 m.y. to about 8.4 m.y. A linear regression model of uniform rate of accumulation of the lava pile with time best fits these data. A growth of 690 m/m.y. is indicated, one lava having erupted on average every 13,000 years. These rates closely resemble those determined for the Borgarfj¿rdur region of western Iceland for the period t=7--2 m.y., and thus it is shown that steady state crustal growth has occurred in Iceland on both sides of the mid-Atlantic ridge for at least 10 m.y. The paleomagnetic polarities in the sequence provide a geomagnetic polarity history which matches closely that derived by Blakely (1974) using sea floor spreading analyses of marine magnetic anomalies. Anomaly 5 is recorded in the section and has lower and upper boundaries of t=10.03 (¿0.34) m.y. and not more than t=8.70 (¿0.36) m.y., respectively. As was proposed by Blakely (1974), at least one brief period of reversed polarity is present within anomaly 5.