The missions which thus represented a slight and temporary revival of the old spirit of enterprise, were those of San Rafael Arcangel and San Francisco Solano. The former, located near Mount Tamalpais, between San Francisco de Assis and the Russian military station at Fort Ross, dates from the 17th December, 1817; the latter, situated still further north, in the Sonoma Valley, from the 4th July, 1823. Some little uncertainty exists as to the true reasons and purposes of their foundation.