AUTUMN IS fast approaching and it would be nice to see the display of fall colors without having to battle the highway crowds to Skyline Drive and other popular viewing spots. Some people need more than leaves to justify a weekend away from home, anyway.

There is at least one place in the area that can provide beautiful autumn scenery and a fascinating group of tourist attractions totally unexpected in their remote spots. It is Pocahontas County in West Virginia, across the Virginia border from the Staunton-Lexington area. The country - more than a four-hour drive from the Washington area - is almost totally occupied by the Monogahela National Forest.

Roads stretch down along, tree-lined valleys and twist up through wooded mountain gaps. But weekend visitors who want to accomplish more than an autumn color drive have to be careful about their timing or they could end up missing some of the attractions.

Probably the most famous site in the county is Cass Scenic Railroad State Park. Old-time steam locomotives pull riders on converted logging cars or open passenger cars up 11 miles of track to just below the second-highest peak in West Virginia, Bald Knob at 4,842 feet.

Lumbering developed into the county's leading industry late in the last century and was made even more lucrative with the arrival of the first railroad in 1899. Three years later, the Cess railroad line was built to give loggers access to the timber at the higher elevations of Bald Knob. The old Shay steam locomotives continued to operate commercially until 1960, when they were no longer economical. The state bought the railroad, kept the locomotives - some of the ast steam Shay engines operating in the United States - and reopened the line as a tourist attraction.

The railway closes down each year at the end of October because of bad winter weather. Until then, one 4 1/2 hour trip all the way to the end of the line leaves from Cess every Saturday and Sunday at noon. The trip winds through forests, into two tight switchbacks, up an 11 percent grade into Whittaker Station, and then through a high, narrow valley, past an old logging town and then on up to Bald Knob. At the top, riders have time for a brief picnic if they brought one, a view of the surrounding countryside from a lookout tower or a short walk through the spruce forest.

Shorter trips are available, stopping at Whittaker Station four miles up the track from Cass. That trip take only 1 1/2 hours, and operates three times each weekend day, at 11, 1 and 3. Weekdays run of both trips are added the first two weeks of October for color viewing, except there will be no Monday trips to Blad Knob.

The longer trips cost $5 for adults, $2 for children 5-11; the shorter is $3 and $1. Narrators deliver spiels on both trips. Some renovation is going on at present. so the ticket counter is located in a dining car bearing red Coco-Cola signs beside the track.

If you look due east from the lookout tower at Bald Knob, across a lower mountain and into the next valley, you'll catch sight of one of the county's other attractions, huge saucer-shaped disks tilting skyward from the Green Bank National Radio Astronomy Observatory. The entrance to the observatory is just south of Arbovale on Rte. 28. Free bus tours of the grounds, which include half a dozen radio television on 2,700 acres, leave every house after a 15-minute film about radio astronomy in the tour center. The tours operate from 9 a.m. to 4 p.m. through the end of October.

Presumably, if some alien beings were trying to contact us via intergalactic radio beams, these hugh dishes would pick them up. But the real purpose of the observatory is "to discover and explain new scientific facts about the universe," which should "help mankind by increasing the breadth and extent of his understanding. It does all that all identifying and measuring signals emitted by celestial objects, one method of mapping outer space that can't be accomplished by the more familiar optical telescope.

One of the first undertakings of the National Science Foundation was the development of the observatory, begin in 1967 and now operated by the Associated Universities Inc, for astronomers from around the world. The observatory was located in Dear Creek Valley because mountains on either side shield it from mountains terrestrial radio interference.

The disk-like telescope include the second largest movable radio telescope in the world, 300 feet across or wide enough to hold a football field. Its main use has been to map the hydrogen gas in the Milky Way and in other galaxies.

About 35 miles southwest, on U.S. 216 just outside of Hillshore, is "The Stulting Place," where Pulltzer Prize-winning author Pearl S. Buck was born June 28, 1892. Actually, it's of little more historial significance than being her birthplace. She was raised in China by her missionary parents. But the home was selected by the author before her death in 1973 to be the repository of her original manuscripts and other memorabilia. The collection is still being assembled.

Buck was the first women to win the Nobel Prize for Literature, awarded in 1938 for a collection of six books on China. Her Pulitzer was awarded for her 1931 novel, "The Good Earth." The Stulting Place, after the maiden name of Buck's mother is open 9 to 5 on Saturdays, 1-5 Sundays, for a $1 admission charge for adults, students 50 cents.

If you're yearning to get back to nature again, just north of Hillshoro on Rte. 39 is a bit of arctic terrain, trapped in an oblong, 750-acre bowl when the Ice Age glaciers receded. The bowl, at an elevation of about 3,400 feet and surrounded by mountains 1,000 feet higher, is called Glades.

It's actually a bog and marks the southernmost point for numerous species of plant life and at least five species of birds. Visitors can hike back into the area or pass through the edges of the bog on a boardwalk built to protect the delicate plant life, including sundew, horned bladderwork, hog orchids and other plants species generally associated with Canada.

Interpretive signs posted at intervals along the boardwalk describe the bog. Generally at 10 a.m. on Saturdays and Sundays, a boardwalk tour sponsored by the U.S. Forest Service is conducted through the Glades. On Oct. 14, the 12th annual Cranberry Mountain Autumn Nature Tour will feature lectures by professional botamists at the bog, beginning at noon.

Other hikes and programs are available from the Cranberry Mountains Visitor Center, just east of the Glades and open on weekends through October. A scenic drive beginning across the road from the center consists of 15 miles of what eventually will be a 100-mile road across mountain ridges, much like Skyline Drive, with valley views on both sides.

Leave plenty of time of this weekend trip if you want to see everything. Because of the more than four hours from the Washington area to Pocahontas County and the hours of the sites, scheduling is difficult. For instance, you might take in the observatory. Buck's home and the bog one day, and the long trip to Blad Knob the next day. There are enough motels in the county, though not many we consider very attractive.

Information for the Glades area can be obtained at Cranberry Mountain Visitor Center, U.S. Forest Service, Richwood, W.Va. 26261 or telephone (304) 653-4826. For Pearl S. Buck Birthplace Foundation, write P.O. Box 126, Hillsboro, W.Va. 24646 or phone (304) 653-4430.

The National Radio Astronomy Observatory is at P.O. Box 2, Green Bank, W.Va. 24944 and (304) 456-2011. Cass Scenic Railroad is Cass, W.Va. 24927 and (304) 456-4300.