Originally Posted by
BobJ
The topic has been discussed before in this very thread, but it was easier to find the original article:
"In the early 1700s, when the Spanish first began exploring what is now Northern California, they came upon San Francisco Bay and were stunned by its beauty and obvious advantage as a safe harbor, as tourists are still stunned today. That it would make a fabulous harbor for a settlement was clear even at first glance. A small Spanish settlement was begun, and western civilization had come to San Francisco Bay. Father Junipero Serra and others began preaching their wares and the settlement prospered. The Spanish were concerned about protecting their settlements and trading posts, and began looking around for a suitable place to install a small garrison. A large promontory in the area that is now Baker Beach was selected as the best place to build a fort to protect the entrance to the Bay. For a number of years, a garrison which varied from a little over 50 to well over 600 men manned the fort on that promontory, guarding the Bay against unwanted incursions.
It was in the great storm of 1772 that the Spanish discovered that the promontory on which they had built their fort was not attached to the mainland, but actually seemed to be what is called now in geological circles a floating island. In fact, they had built their fort on what apparently was a large pumice plug, blown loose at some time from a volcano in some gigantic eruption. There are theories that the volcano in question is Mount Rainier, which was certainly far more active in prehistoric times than it is today. Pumice, as everyone knows, is a fairly light, very porous rock having a density of just about 58 pounds per cubic foot, or a little more than 10 percent lighter than seawater. In other words, this stone can actually float, as is usually demonstrated in high school physics class. In fact, as it turns out, what we call Alcatraz Island is not an island at all, but a very large hunk of some prehistoric eruption which is composed mainly of pumice at its core but, of course, with crusts of heavier igneous rocks in its shell. It isn’t as buoyant as a ping-pong ball, but it is buoyant enough, as the Spaniards discovered in the 1772 storm, when the waves washed what we now call Alcatraz Island off the beach and moved it farther east, even closer to the Bay entrance. Luckily, for some reason, it seems fairly stable in its present “upright” position, and the Spanish fort was not damaged, although the garrison was pretty shaken psychologically to find themselves winding up six miles further east at the end of the storm.
In those days, of course, science was a good deal less highly developed than it is now, and the Spanish saw this as an omen warning them that the way they were treating the native inhabitants of the area was not in keeping with the Christian beliefs they espoused and many students of the social sciences and the history of that time are convinced that this gave rise to the incredible efforts to treat the natives more kindly by establishing missions and churches up and down the coast for their education and betterment. In any case, the Spanish fort and garrison stayed in that location for a long while, as can be seen in the very well known mural at Mission Isabella which shows the fort in that location and, of course, shows no island where we now have Alcatraz. When I first visited Mission Isabella and looked at the mural, for a long while I couldn’t figure out what looked so odd about it. Of course, the City of San Francisco with the built up skyline, Coit Tower, the Pyramid, and the Golden Gate Bridge are not there, and it is interesting to see a view of the area when there was nothing but hills, grass, etc. However, it finally dawned on me that Alcatraz Island was missing, and this was another clue that had not been connected previously to explain the mystery.
It was in the mid-1800s when California became a state that the U.S. federal government decided to move the fort and garrison from China Beach further into the Bay to what is now called Fort Point. Very few people realize that Fort Point derived its name from the original fort built on the pumice plug rather than the fort that was built on solid land later on. The fort was rebuilt and expanded, I think, in about 1865 or so, at which time the old fort was completely torn down to make way for the new one. The U.S. Army took advantage of an extremely high tide and decided to move the fort even further into the Bay and anchored it offshore. It served as a perfect blocking fort for the San Francisco Bay entrance, but as there became less and less need for a fort, it was moved to its present location, using the original Spanish anchor chains and anchors to secure it. The original Spanish chain was a fantastic piece of iron work, apparently forged by one of those magnificent steam forges in use during that time. The links are severely worn away where they would join with one another. The links were raised by a fisherman in 1923 when he fouled it with his gear. The link will soon be on display next to the section of cable from the Golden Gate Bridge in the San Francisco Golden Gate Bridge museum.
Anchoring: The original Spanish anchoring array was a group of three anchors at approximately equal angles from the island, which served until the famous attempted escape from Alcatraz prison portrayed in the movie with Clint Eastwood. It is interesting to note that, at that time, even though Alcatraz was no longer used by the Federal Bureau of Corrections, they still had a secrecy blanket on the fact that the basic constituent of the island was pumice. The reason for this, of course, is that they thought they might very well need the prison later on and didn’t want this fact to be known. Frank Morris, the con who escaped from the island apparently had done his homework, and in the movie where you see him digging through supposedly rotting concrete, in fact he actually dug through pumice, which is quite soft. The Hollywood filmmakers had to rewrite those details to keep the secret. Obviously, no one that I know of has actually ever seen “rotten” concrete. It is one of the glories of Hollywood that they were able to make so many people go along with the gag that he used a soup spoon from the mess hall to supposedly dig through “rotten” concrete. In fact, he was digging through pumice, as many of us have done in high school or college classes. Apparently what had tipped Morris on to the idea was that he had noticed from his cell window that, on a strong ebb tide in the spring when there was a lot of water flowing down from the rivers to augment the ebb tide, the island seemed much closer to San Francisco than usual. He made a very crude surveyor’s instrument which he could use from his cell window, and determined that during certain combinations of ebb tide and river flow, the island actually moved nearly 160 yards closer to the San Francisco shore. Apparently he thought this was just the margin he needed to assure his ability to swim to shore. (Most sailors here in the Bay have had similar experiences with the island moving somewhat in tidal currents. Who hasn’t had the experience of feeling certain that they could sail to weather of the island without a tack, only to find at the last minute that the island had moved just enough to force a tack offshore?) This attempted escape gave the prison authorities serious worries and led them to request that the Army Corps of Engineers do a more careful survey of the area around Alcatraz in which they found that one of the old Spanish anchors had dragged considerably. The drift, together with the wearing between the links, had added this approximately 200-yard slack in the anchoring system. It is not known for certain, but there was some suspicion that the anchor chain might very well have been snagged by a Japanese midget submarine, however, that is a totally unsubstantiated rumor.
As is usual with anything federal, the original budget for replacing the anchoring array with more modern equipment began at an estimated cost of $32 million, and wound up costing you and me, the taxpayers, nearly $182 million, including the casting of four stainless steel anchors, each weighing about 26 tons, and connected to the island with stainless steel cables and a rather sophisticated water cylinder damping system. The new anchor array was installed under the guise of yet another Army Corps of Engineers survey of the area. The anchors and cables were laid during the early morning hours, when the fewest people might be around. One side benefit from this last operation was that the cable layer was easily converted to its present use, and we have all seen it at one time or another wandering around the Bay collecting flotsam, jetsam, and debris in the forward scoop area in which used to be mounted the stainless cable laying guides.
The future of Alcatraz is somewhat uncertain. Although not made broadly public, there was apparently some talk a few years back about moving Alcatraz once again, either somewhere into the South Bay or perhaps up in the shoals near San Rafael, or even as far up as Carquinez to serve as a place on which the federal or state government, it was never clear which, would build low-cost housing. Unfortunately, as it turned out, owing to the silting upon the Bay from soils carried down from the rivers, Alcatraz seems to be firmly aground at present and the next tide high enough to float it once again will come in the year 2014 By that time, it is hoped that we will have found some other way to deal with the problems of the homeless and the need for low-cost housing, but it certainly would be grand to see the Bay once again open as it was when the Spanish explorers first came here."
Gary Mull, 1990 © Copyright 1995, BAY & DELTA YACHTSMAN
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