The terrain mostly consists of an Appalachian oak forest region featuring broad lowlands broken by traprock ridges.
Open expanses of lowland alternate with broken mountain country, cut by deep river gorges and harbouring upland basins such as that in which Sofia lies.
The soils within that zone that cover loess are excellent loams; lowland clays, when broken down, also exhibit high quality, as do alluvial soils; in contrast, areas covered with dry, sandy, or gravelly soils are more useful for residential and amenity purposes than for farming.
In the western section, which occupies some two-fifths of Russia's total area, lowland plains predominate over vast areas broken only by low hills and plateaus.
This divide is broken by occasional cols (depressions) and lowland corridors, notably the Langres Plateau, across the Jurassic outer rim of the Paris Basin.
The Mackenzie Lowland is only about 30 miles wide in this section, being broken by the treeless summits of the Franklin Mountains, which rise to elevations of little more than 3,000 feet (900 metres) on the east side of the river.
Ewes take their lambs with them to the mountains each spring and pass on these skills, and if the cycle is broken, the herd cannot simply be replaced with less hardy lowland breeds, according to Martin Lewes, a farming expert at the local Radio Cumbria.
In the lowlands deep glacial deposits filled eroded surfaces and produced a smoother landscape, often broken by low ridges and hills of glacial material, drumlins, rogen (ribbed) moraines, and eskers.
It comprises an upland region that is forested with hardwoods and broken by river valleys, except for the south, which consists of coastal lowlands, and several small islands in the sound.
To the south, another lowland extends along the shores of the Black Sea and the Sea of Azov; its level surface, broken only by low rises and shallow depressions, slopes gradually toward the Black Sea.
