The beginning of the end of California as an island

Father Eusebio Francisco Kino's important map of California, drawn in 1702 but not published until it was included in Joseph Stöcklein's 'Allerhand So Lehr-Als Geist-Reich Brief, Schrifften und Reis-Beschreibungen, welche von denen Missionariis'.
Kino (1645-1711), an Italian Jesuit, travelled to New Spain in 1682 and stayed there the rest of his life. He travelled extensively and used his knowledge of astronomy and mathematics to compile maps of the region. Although he never crossed to California by land, his observations from a high point near the Colorado River, from which he saw only land to the west, caused him to state California was a peninsula. It was nearly another half-century before this was proved.