A Horizon

{
  "id": "MLC-T-ENV-000095",
  "term": "A Horizon",
  "field": "Environment",
  "definition": "1. The top layer of soil. Plant and other organic debris builds up in this layer. This is the part of the soil generally referred to as 'top soil'.\n\n2. The uppermost mineral layer, often called the surface soil. It is the part of the soil in which organic matter is most abundant, and leaching of soluble or suspended particles is typically the greatest.",
  "references": [
    "USGS Geology in the Parks",
    "EPA Mountaintop Mining Valley Fills Draft Environmental Impact Statement Glossary at http://www.epa.gov/region3/mtntop/pdf/VIII_Glossary.pdf"
  ],
  "url": "https://mlchart.com/terminology/environment/a-horizon/"
}