Oakland Geology

After Pedro Fages came through the East Bay in 1770 and 1772, no one from New Spain appears to have visited the land on which Oakland sits until Juan Bautista de Anza led an exploring expedition here in the spring of 1776. Scholars seem to be quite sure of where the group went, but when I examine the record I find more and more room for interpretation and inference.

I’m not going to pretend I’ve examined the manuscripts or know 18th-century Spanish. I’ve accessed translations of those manuscripts and, well, here’s some of the questionable things and wiggle room I see in the record.

• Neither Anza nor the group’s diarist, Father Pedro Font, had been with Fages in the earlier visits, so they had only Fages’s records to compare against the countryside they saw. We can’t rely on their interpretation, especially as it appears they took a different route than Fages.
• We can’t rely on their directions. The East Bay from Berkeley south is persistently slanted 33 degrees west of north (thanks to the Hayward fault and the plate boundary of which it’s part) making it hard to eyeball true directions; magnetic north was apparently 12 degrees east of true north at the time (thanks, NOAA); and Font complained about the poor quality of his compass, so the explorers’ impressions are suspect. The men were not experienced sailors either, people I might trust, but army soldiers. Moreover, I wonder about the transcriptions. There seem to be too many instances of “northwest” (noroeste) and not enough of “northeast” (noreste) to fit the written route on modern maps. And the scholars, whom I trust on this topic, point out that very discrepancy between different copies of these documents, all of which were made by hand.
• We can’t rely on their distances. No one had odometers. Font did his best, prefacing his notes with a discussion of the length of the Spanish league (approximately 2.6 miles, apparently), but even so the men were on horseback whereas Fages had been on foot. On the day they came through Oakland, Anza wrote down that they went “about ten leagues” while Font put it at “some fourteen leagues.” The day’s ride was long, from Hayward to Pinole, and the group was in a hurry, with their goal still ahead of them. (And just as Fages had complained in 1772, the Anza party was beset with mosquitoes all that day.)

Long story short, I think that whereas Fages mostly skirted the Fan as he sought (and failed to find) an easy level route through Oakland, Anza rode pretty straight through it.

Anza’s group set out from their camp on San Lorenzo Creek, in present-day Hayward, that morning at 7 and rode along the foot of the hills, with a jog upstream to get across the deep arroyo of San Leandro Creek, and then on to the edge of the Fan, the hill of Pleistocene gravel occupied by Evergreen Cemetery, in the lower right corner of this digital elevation model.

Where Fages turned left to stay on the flats, Anza headed the horses straight, toward a promising gap in the hills,

and into the Allendale flat. Almost fifty years later, Luís Maria Peralta’s family would put the first hacienda on their huge East Bay land grant there, just across Peralta Creek. “About two leagues” after crossing San Leandro Creek into Oakland territory, Font wrote that they “crossed a small arroyo without water and almost without trees,” which I think was Peralta Creek. “Then a little further on we ascended a hill which is on a straight line with the mainland and the plain which runs toward a very thick grove of oaks and live oaks on the banks of the estuary,” where he sketched the view toward the Golden Gate. That is this drawing, showing the Alameda peninsula flanked by San Leandro Bay on the left and the Estuary on the right:

In my interpretation, he would have been sitting on the ridge where Patten University sits today but higher up, maybe where Lincoln Avenue starts today. It also could have been down on Carrington hill; both ridges line up with the Alameda peninsula, which was a large encinal (live-oak grove) at the time.

“Then, descending the hill, we crossed another arroyo almost without trees and with some little pools of water which did not run. This appears to be the arroyo which Father Crespi called the Arroyo del Bosque and which empties into the extremity of one arm of the estuary.” He refers to Sausal Creek as described by the Fages party in 1772.

“We continued the journey over hills and plains, crossing two more arroyos with little water, deep beds, and a heavy growth of trees, the second one having more than the other, and both of them flowing into a bay which the arm of the estuary forms on this side.” These I interpret as Indian Gulch and Pleasant Valley Creeks, which clearly both drain into Lake Merritt, which was then a narrow inlet with wide mudflats. I don’t think the group went near the Lake but instead were higher up the valleys — they were on horseback, after all.

“Afterward we entered a plain in which we crossed two small arroyos without water.” Finally they had left the hills of the Fan and were back on the East Bay plain. That would make these two streams Temescal and Strawberry Creeks. “From this plain we clearly descried the mouth of the port, and when the point of the red cliff on the inside was in line with the outer point of the mouth, I observed the direction in which they ran, and saw that it was to the west with some declination to the south.” That matches the view of the Golden Gate as seen from Berkeley.

Oakland remained something of a distant place until the San Francisco and San Jose missions had captured or driven off the native people and established their own purposes on the territory: food and fodder cultivation in the Richmond area and cattle range in the flats from Fremont to East Oakland.

I want to note that Fages and Anza did not come as conquerors. Their assignment, at the dawn of Alta California, was to establish friendly relations with the natives. They exchanged gifts with every group they met: glass beads, generally; and a surprising number of native groups gave them duck decoys in addition to food. The situation did not last. The priests could not even perceive the fine-tuned ecosystem in which the Ohlone were the keystone species, only naked children of nature who must be trained in their own god’s image.

Oakland was visited soon after the missionaries of New Spain established their capital port city at Monterey, in 1769. The area’s unusual terrain gave them trouble, and part of the reason was the set of treeless hills of sand and gravel in its midsection that I call the Fan. The Fan interrupts the nice clean plain that otherwise extends the whole East Bay. Here’s how it looks in a digital elevation model and the geologic map. (As always, click to enlarge.)

The first Europeans to have stood where Oakland sits were four scouts under the leadership of Spanish-born army captain Pedro Fages, who came from Monterey to the East Bay in November of 1770 with a party of six soldiers and a muleteer. It was a short reconnaissance visit that Fages, a seasoned leader who earlier that year had been left in charge of Alta California, made on his own initiative.

In the first part of his trip, Fages pioneered the route inland from Monterey that is traced today by U.S. 101. He then made his way up the East Bay, making camp at San Lorenzo Creek in present-day Hayward, near where scouts from the Portola expedition had apparently stopped the previous year. Fages’ notes are vague; this is the entire record of the day:

November 28. — Four soldiers set out to explore the country, and at night returned saying that they had travelled about seven leagues to the north; that the country was very good and level; that they had climbed to the top of a hill but had not been able to see the end of an estuary which lay before them and which communicated with the one which lay at our feet; that they had seen many tracks of cloven hoofs which they thought were of buffalo; that close to the hills which they passed at the right there were some springs of water; and that they had crossed two small streams of it. They said, also, that they had seen the mouth of the estuary, which they thought to be the one which entered through the bay of the port of San Francisco. This I confirm through having seen it.

(Some explanation: The Spanish league is a little over 2-1/2 miles. The “estuary which lay before them” refers to San Pablo Bay and the one “at our feet” refers to San Francisco Bay. The “port of San Francisco” means Drakes Bay, the “bay of the port of San Francisco” is the bight between Point San Pedro and Point Reyes, and the “mouth of the estuary” is the Golden Gate.)

The men apparently hiked a total of about 16 miles, or 8 miles each way, as estimated by walking. If that whole route was “very good and level” ground, they must have stayed on the flats, and they must not have reached San Antonio Slough (present-day Lake Merritt), which they would have noted because it blocks the way pretty definitively. They were passing the hills overlooking San Leandro and the lower hills of the Fan “at the right” and crossed “two small streams.” These would have been San Leandro and Sausal Creeks, at their lowest flow early in the rainy season.

The hill they climbed, I think, was the hill of San Antonio Park: it was near where they must have turned back, and from its top can be glimpsed parts of San Pablo Bay and the gap of the Golden Gate, although the actual water passage is not visible. Fages “confirmed” the sighting because he could see the gap, though less clearly, from where he spent the day in Hayward. The presence of the Golden Gate was known from the 1734 voyage of Cabrera Bueno, but it had not yet been charted. Here’s the inferred route.

And on the Bache map of 1857 I show the hill’s location with an X. At that time it was a lookout station for the Brooklyn harbor; today it’s a park that still has good views.

And here’s the topography in detail.

Fages returned in the spring of 1772 to push farther north. This time it was a proper expedition that included 12 soldiers, a muleteer, an Indian guide and a priest, Juan Crespi, whose diary served as a formal record. Their primary goal was to fix the position of the Golden Gate in preparation for founding the San Francisco mission; secondarily they sought to find a way around San Pablo Bay. Oakland, with the hilly maze of the Fan and the inconvenient slough in its midst, was in the way.

Leaving the familiar campsite in Hayward on 26 March, they hiked four leagues. Crespi recorded that they crossed five creeks, “three of them medium-sized and two very large, their banks grown with alders, cottonwoods, live oaks, and some laurels.” By my count these would be San Leandro Creek (large), Arroyo Viejo (small), Lion Creek (small), Peralta Creek (small) and Sausal Creek (large).

At the end of four leagues we halted not very far from an arm of the estuary [Oakland Estuary/San Antonio Creek], which forms with another [San Leandro Bay] something of a peninsula [Alameda], where there is a grove of live oaks, which one can enter only from the mainland side. The camping place is about four leagues from the principal estuary or arm of the sea, which we made out from this place very well, and it looks like a sea to us.

I place the camp’s location near Foothill Boulevard west of Sausal Creek and not, as others have done, up near Mills College. Crespi observed, “The site is very suitable for a good settlement; for on account of the proximity of the forest they could provide themselves with timber and firewood. This place was called Arroyo del Bosque.”

The next day they set out early heading north-northwest, but then ran into the wide tidal channel of Lake Merritt: “Because of the estuary [San Antonio Slough] which surrounds the wood [Alameda] and penetrates into the land about four or five leagues until it heads in a mountain range, we were compelled to travel about a league and a half by some ranges of hills, which, although they are all treeless and grass-covered, annoyed us very much with their ascents and descents.”

This part of town is still up and down. The land seen by the Fages party differed from modern Oakland in that the creeks feeding Lake Merritt — Indian Gulch, Wildwood and Pleasant Valley Creeks — were not culverted and paved over with nice asphalt streets, but wide marshy tracts extending well away from the Lake, especially at this time of year. The detours were surely tedious. The mosquitoes, too, drove them all nuts.

After three leagues of trudging they came out on the other side of the Fan. My idea of their route was up Grand Avenue, over the ridge at Linda Avenue, across the valley of Glen Echo Creek and over the last low ridge of the Fan on 41st Street. At this point the party “entered an immense plain,” and they saw for the first time the Golden Gate itself.

They stopped for a while to observe it closely, and Crespi noted its features accurately. We can approximate this view today from the crest of 40th Street Way. They went on to the northwest that day for another league and into history, leaving the territory of Oakland on good terms. They didn’t return this way but instead walked up toward the Delta and looped back south through present-day Walnut Creek and Pleasanton. The next visitors to Oakland were the Anza party in 1776.

DEM images from the National Map site, route maps from gmap-pedometer.com