Jacob Marlin and Stephen Sewell, the first residents of European descent in the Greenbrier Valley, had established themselves by 1749 at the mouth of Knapps Creek, the present site of Marlinton, Pocahontas County. They were discovered living there by surveyors John Lewis and his son, Andrew, in 1751. Marlin and Sewell had built a cabin together but later argued over religion and separated. By the time the Lewises found them, Sewell had moved from the cabin to a nearby hollow sycamore tree as the best way to avoid further dispute and preserve his friendship with Marlin.

The two men may have been land scouts rather than actual settlers, and soon afterward Sewell was among a group of 18 who received a large land grant north of the Greenbrier River. He and Marlin permanently parted ways some time after the Lewises came upon them at Knapps Creek. Sewell later built a cabin on the eastern side of Sewell Mountain on what is now known as Sewell Creek near present Rainelle. He was killed by Indians, apparently at the cabin site and probably in 1756 during the French and Indian War. Marlin, who returned to the East, survived the Indian wars.

Marlin and Sewell were among the very first English colonials to establish themselves on the "western waters," those streams flowing westward to the Gulf of Mexico rather than eastward to the Atlantic. Their remarkable story soon became part of regional folklore and history. They left their names on the map of the area, including most notably the town of Marlinton and Sewell Mountain, but also a dozen more streams, mountains, and other places.