A horizon
Where earth meets sky
The A horizon is the topmost layer of mineral soil, sitting just below any surface organic matter.
It's where most biological activity occurs—roots, earthworms, microorganisms—and where organic material mixes with mineral particles to form dark, fertile topsoil.
Farmers and gardeners work primarily in the A horizon.
In soil science, horizons are designated by letters: A near the surface, B below it, C above bedrock.
- skylineUrban profile against atmosphere
- sunsetDay yielding to darkness
- vistaPleasing distant scene
- distantFar away or aloof
- edgeBoundary or sharpness
boundary · soil · earth · layer · topsoil · humus · geology · profile · stratum · limit · expanse · view · panorama · vanishing point · endless · far · far off · gaze