"Here yesterday on the Pilon just out of Tucson I saw the same kinds of rocks of in much smaller pieces. To me it is clear that originally there was our Rillito Creek and that the Bahada descended regularly to Tucson and in this way the grains of the Santa Catalina the grit to north Tucson. The climate must then have been drier with no influence into the Santa Cruz, and perhaps then was then our Santa Cruz River. Re- cently the climate has become warmer and the streams are now see are cutting through the Pilon, gulching the Bahada, and slipping the north side of the Pilon into the Rillito Creek. Working along these drifts I think some interesting physigraphy could be developed here. The Santa Catalina rocks are all of Pre Cambrian granites, gneisses and schists that farther north are intruded by younger granites - the Post Carboniferous granite,"