CLAREMONT, Calif.—An anonymous donor has given at least $100 million to The Webb Schools in the largest donation ever made to an independent high school west of the Mississippi, officials have announced. The donor, a Webb alumnus, is making the gift “to honor his parents for their wisdom and sacrifices in sending him to Webb, and as a recognition for Webb’s indelible impact on his life,” school officials said Saturday. The Webb Schools is the collective name for two private schools for grades 9-12, founded by Thompson Webb in 1922. The schools include Webb School of California, Vivian Webb School, and the Raymond M. Alf Museum of Paleontology, the only accredited museum of paleontology on a high school campus. “This transformative gift at least $100 million will enable Webb to dramatically expand access to our unique, unbounded program to the very best and deserving students regardless of financial circumstance,” Head …