The opening of a new race course at Morven Park in Leesburg, Va., the doubling of the purse for the American Grand National at Foxfield, Va., and the absense of a fall meeting at Fair Hill, Md., for the first time since 1953, are major changes of a fall steeplechasing season that opens Wednesday. The first meet is the Rolling Rock races at Ligonier, Pa.

"The course is okay . . . it looks real good," said Dr. Joe Rogers, race chairman of the Morven Park meeting, which holds its inaugural session Saturday, Oct. 4. "All we need now are some horses."

The new course, which was laid out last spring and planted in grass last fall, is a 1 1/4-mile track with both brush and timber layouts. It adjoins the Morven Park International Equestrain Institute.

"The dry spell hasn't hurt us too much," said Rogers, "we're just suffering from first-race jitters and losing a little sleep along the way."

Raimie Woolfe, chairman of the Foxfield event outside Charlottesville, is delighted with the backing of the Paul Masson Vineyards of Saratoga, Calif., that has enabled him to raise the purse for the Amercian Grand National to $20,000.

"It's the oldest steeplechase in America," he said, "and it deserves to carry a good purse." The race was first run in 1899 at the old Morris Park track in New York and later at Belmont Park and Fair Hill. In 1979 it was switched from Fair Hill to Foxfield.

The lack of a Fair Hill meeting is one of the biggest blows to the sport. One of the finest steeplechasing courses in the country, Fair Hill concluded a successful spring meeting in June but was unable to get a fall date from the National Steeplechase and Hunt Association in time to stage a meeting.

Fairfax will open the area season on Saturday, Sept. 20, with its annual six-card at Belmont Plantation on Rte. 7 near Leesburg. The Bowman Bowl, at three miles over timber, will feature the program.

Fairfax will be followed on successive Saturdays by Foxfield, Morven Park and the Virginia Fall Race meeting at Glenwood Park in Middleburg, Va. The Montpelier race meeting near Orange, Va., will close out the Virginia schedule on Nov. 1.

Belmont Park offers two days of steeplechasiang on Oct. 9 and 10, the later date featuring the $40,000 Temple Gwathmey. The season closes with the $50,000 Colonial Cup in Camden, S.C., on Nov. 16.