The phrase "a flat stretch of" is correct and usable in written English.
It can be used to describe a level, even area of land or surface, often in geographical or physical contexts.
Example: "The hikers enjoyed a flat stretch of trail that allowed them to catch their breath before the next ascent."
Alternatives: "an even expanse of" or "a level area of".
Before the steep hill to our house was a flat stretch of fifty feet.
Q. Black Rock Desert, a flat stretch of about 1,000 square miles, is so desolate it's used to launch rockets.
He swooped in above a flat stretch of land near our campsite, and, descending too quickly, made a rough landing on his coccyx.
It was not clear if the weather had anything to do with the derailment, which occurred about 1.20pm ET along a flat stretch of rail.
On a flat stretch of road on the southeast edge of Little Rock sits the sand-colored Sri Radha Madhav Welspun Temple, a place of Hindu worship by the Arkansas River.
St. Martin's Neck Road in the Isle of Wight Wildlife Management Area is perfect: a flat stretch of asphalt that meanders through a saltwater marsh, then past chicken houses, farm plots and cornfields.
Every summer, Jack Field takes his herd of about a hundred cows to graze in the same floodplain — a low, flat stretch of land next to a river — in Yakima, Wash.
For the past 15 years, Carl Weiss looked out his Westhampton Beach front window onto a drab, flat stretch of yard.
We then pushed on through a fairly flat stretch of countryside along the busy A26 until we turned right on to the famous Causeway Coastal Route.
3.34pm: The camera cuts to Thomas Voeckler, who looks like he's struggling badly, even though his group is tackling a comparatively flat stretch of asphalt at the moment.
Now, what urban Americans tend to picture when we hear the word "farm" is a broad, flat stretch of corn stalks extending to the horizon -- the sort of setting through which that cropduster chased Cary Grant in "North by Northwest".
