President Clinton has scheduled a trip for this Saturday to California’s Sierra Nevada, where he is expected to announce the creation of a new national monument to protect groves of giant sequoias. The monument, which Clinton can designate without approval from Congress, could encompass as much as 355,000 acres of land now in the Sequoia National Forest. Names being considered include the California Big Tree National Monument and the Sierra Nevada National Monument. The Sierra Club and other green groups have been pushing Clinton to create the new monument, while the area’s members of Congress have been lobbying against it.