The blaze was burning on the south side of Gravel Ridge, west of Highway 107 and north of Oakdale Road, away from any structures.
The fire was reportedly the source of the smoke smell across parts of northern Pulaski County Thursday morning.
The Arkansas Forestry Commission was on the scene with a bulldozer, plowing a line around the fire.
According to John Robinson, forecaster with the National Weather Service (NWS) in Little Rock, on clear, calm nights, a temperature inversion usually occurs. An inversion is a layer of warmer air aloft, typically a few hundred to a few thousand feet above the ground.
The NWS's weather balloon release Thursday morning showed the inversion was about 600 feet above the ground. Smoke can rise only as high as the inversion, then it spreads out horizontally, typically covering a fairly large area. Robinson says that means when a fire happens late at night or early in the morning, people can often smell smoke well away from where the fire was.
Gravel Ridge Fire Chief Andy Traffanstedt said that peat moss and some trees and shrubs were what was burning in the swampy area. Peat moss fires are notoriously difficult to extinguish. The fire can smolder for a long time, then flare up again In this case, today is the 7th time that firefighters have been to this fire in a week and a half.