Herber L. Block of The Washington Post won his third Pulitzer Prize for cartooning, and the 2,600-circulation weekly Point Reyes Light in northern California won the Pulitzer public service award for its exposes of Synanon, Comlumbia University President William J. McGill announced today.

Edwin M. Yoder Jr. the editorial page editor of The Washington Star, won the 1979 prize for his editorials covering a range of topics, and the Baltimore Evening Sun's science writer, Jon D. Franklin, was named the first winner of the Pulitzer in the new category of feature writing for his two-part account of a brain operation.

Nineteen awards, all except the public service award carrying a prize of $1,000, were given for journalism and letters, drama and music.

Russell Baker of The New York Times won the commentary award for his Observer column. James Risser of the Des Moines Register won the national reporting award for the second time for a seven-part series on pollution caused by farmers. Articles by Richard Ben Cramer of the Philadelphia Inquirer on the effect of war in the Middle East on individuals won the prize for international reporting.

Robert Penn Warren, 73, won his third Pulitzer for his "Now and Then: Poems 1976-1978." Warren won the 1958 Pulitzer for poetry and the 1947 prize for fiction for his novel "All the King's Men."

John Cheever, 66, won the fiction prize for his collection of 61 short stories, "The stories of John Cheever."

The drama prize was won by Sam Shepard, 35, for "Buried Child," which just concluded an off-Broadway run at New York's Theater de Lys.

Block, better known as Herblock, became only the second winner of three Pulitzers for cartooning. Herblock, 69, joined The Post in 1946 after working for the NEA Service for 10 years.

He won in 1942 and 1954 for specific cartoons, but his third prize honors the whole of his work, Typical of his 1978 cartoons was one published Aug. 31 and quoted by the Pulitzer Prize Board.

It comments on Judicial decisions limiting reporters's freedom.

A Roman judge is portrayed handing a soldier a "license to fish through notes, memos and anything else belonging to members of the press." The caption reads: "And bring me their heads so I can see what goes on inside them."

The only other three-time winner for cartooning was Rollin Kirby who won all his prizes in the 1920s. Kirby worked for the New York World, which was published by Joseph Pulitzer under whose will the annual prizes are awarded by Columbia's president upon the recommentation of the Pulitzer Prize Board.

The public service gold medal winner, the Point Reyes Light, looked into the practices of Synanon over several years because Synanon's local headqaurters in near the newspaper in western Marin County, Calif.

Synanon began as a drug rehabilitation clinic, but changed in time, becoming best known in the last year for allegedly planting a rattlesnake with its rattles removed in the mailbox of an attorney who had become a foe of Synanon.

Legal actions Synanon had stopped several other news organizations from continuning exposes of the organization, but the tiny Point Reyes Light-which has only one full-time reporter-continued to cover Synanon. The weekly's copublishers are David Mitchell and his wife, Catehrine, who have been with the newspaper since 1975.

The general local reporting award was won by the San Diego Evening Tribune for its deadline coverage of the nation's worst air crash. On Sept. 25, 1978, a Pacific Southwest Airlines 727 and a private plane collided near San Diego Airport.

Within 90 minutes, the Tribune staff had prepared a lead story and six sidebars. The papers's last edition, which was on sale less than six hours after the crash, carried 10 stories.

Gilbert A. Gaul, 27 and Elliot G. Jaspin, 32 of the Pottsville Republican in Pennsylvania, won the special local reporting Pulitzer for a year long investigation of the deliberate destruction of a coal company by a group with ties to organized crime.

The Blue Coal Corp., which was once a leading producer of anthracite, was dismantled after takeover by a group that once included Jimmy Hoffa. Its demise left Pennsylvania holding about $20 million in bills.

The criticism prize was awarded to Paul Gapp, 50, for his architecture criticism in The Chicago Tribune.

For photography, Thomas J. Kelly of the Pottostown Mercury in Pennsylvania won the spot news prize for a series of photographs of a siege in which a young man held his family hostage. The 16 photographers of the Boston Herald American won the feature photography prize for their pictures of the February 1978 blizzard that crippled Boston and parts of New England.

In letters and musci other winners were:

Harvard Professor Edward O. Wilson, 49, for his book "On Human Nature." Wilson's book, which combines theories of evolution, ecology and ethology in what has become known as sociobiology, won the award for general nonfiction.

Don E. Fehrenbacher, 58, for "The Dred Scott Case: Its Significance in American Law and Politics." Fehrenbacher, a professor at Stanford, won the history prize.

Leonard Baker, 48, who won the biography prize for "Days of Sorrow and Pain: Leo Baeck and the Berlin Jews," an account of a rabbi who helped German Jews to escape and to survive when the Nazis came to power.

Joseph Schwantner, 36, for his orchestral composition "Aftertones of Infinity." Schwatner has written more than 25 major works. He is also an associate professor of composition at the Eastman School of Music in Rochester, N.Y.

The Pulitzer Prize Board made its recommendations during a meeting at Columbia University April 6. CAPTION: Picture, Pulitzer Prize-winning cartoonist Herbert L. Block at his drawingboard. By Douglas Chevalier-The washington Post