An archeologist says he has discovered the foundation of what may have been a Gold Rush saloon and "extremely important" artifacts under a San Francisco site where construction is planned for a 26-story building. Archeologist Allen Pastron hopes to persuade the developers to delay work until the site in the financial district is documented by photographs, measurements and notes. The foundation and the artifacts may result in "the best, systematically researched example of a Gold Rush structure in archeological terms in San Francisco," he said. The archeologist found the intact brick floor of a building that he estimates was built in 1850 or 1851. The artifacts include a blue glass bead like those traded to Indians, glasses and whiskey and champagne bottles.