Basalts recovered from sites 100 and 105 of leg 11 of the Deep-Sea Drilling Project are mineralogically and chemically similar to basalts from ridge and near-ridge sites. Textural evidence suggests that the units sampled were extruded as thin flows and are presumably the products of midocean ridge volcanism shortly after the opening of the North Atlantic in the middler to late Jurassic. Chemical evolution of the liquids sampled at site 105 basalts have experienced clinopyroxene fractionation, presumably at pressures in excess of about 10 kbar. Models for the abundances of incompatible trace elements in the source regions of these basalts suggest 2--3 times chondritic heavy rare earths at both sites, 0.5--1 time chondritic Zr, Hf, Nb, Y, and La at site 105, and 1--2 times chondritic Zr, Hf, and Nb at site 100. Two site 100 samples have variable La/Yb ratios which reflect inhomogeneities in the upper mantle. There is no indication that the source regions for North Atlantic midocean ridge basalts has evolved since the late Mesozoic.