More from The Discovery of San Francisco Bay. The Portolà Expedition of 1769-1770 (the diary of Miguel Costansó). Having crossed the entire Los Angeles basin from south to north (and having experienced several minor earthquakes), the explorers found further progress northwards blocked by a mountain range extending east to west in both directions. They resumed their journey having camped somewhere near the present-day UCLA campus [footnotes are mine]:
__________________________Saturday, 5 August : The scouts who had set out to examine the coast and the way along the beach returned shortly afterwards with the news of having reached a high, steep cliff, terminating at the sea where the mountains end, absolutely cutting off the passage along the shore.  This forced us to seek a way through the mountains, and we found it, although it was rough and difficult. We then set off from the Ojos del Berrendo in the afternoon, and, directing our course to the northwest towards the point where there seemed to be an opening in the range, we entered the mountains through a canyon formed by steep hills on both sides.  At the end of the canyon, however, the hills were somewhat more accessible and permitted us to take the slope and, with much labor, to ascend to the summit, whence we discerned a very large and pleasant valley. We descended to it and halted near the watering-place, which consisted of a very large pool. Near this there was a populous Indian village, and the inhabitants were very good-natured and peaceful. They offered us their seeds in trays or baskets of rushes, and came to the camp in such numbers that, had they been armed, they might have caused us apprehension, as we counted as many as two hundred and five, including men, women, and children. All of them offered us something to eat, and we, in turn, gave them our glass beads and ribbons. We made three leagues on this day's journey. To the valley we gave the name of Santa Catalina;  it is about three leagues in width and more than eight in length, and is entirely surrounded by hills.
 Pacific Palisades at Santa Monica.
 "Ojos de Agua del Berrendo"--Antelope Springs--was a watering place so-named the previous day because the explorers had caught a wounded antelope there.
 Sepulveda Pass.
 The San Fernando Valley. Santa Catalina is now the name of an island west of Los Angeles.
Sepulveda Pass as it appears today, channeling the 405 freeway: