This project is for study of temporal variation of 3He/4He on Gran Canaria, Canary Islands. A variety of phenocrysts types throughout the stratigraphic section at Gran Canaria will be studied. Results will provide constraints of different magma types at Gran Canaria. Geochronology of the samples will be attempted using (U + Th)/ He and compared with Argon ages already available. %%% Helium isotopes provide an important constraint on the source of magmas generated in the lithosphere and upper mantle. The study at Gran Canaria is especially important because isotope data presently available is inconsistent with geophysical data relating to the Canary hot spot.