Riserva Naturale Regionale Oasi WWF Calanchi di Atri

The reserve set up in 1995 where there was a WWF Oasis, enclosing forms of erosion here take on a striking appearance: the badlands, also known as pits or Dante scrimoni are produced by the runoff of 'water on clay and marl soils were devoid of forest cover .

The protected area covers 600 hectares on a hillside between 100 and 500 meters, from the river valley to Piomba Justice Colle.

The badland landforms are distributed mainly on the side of the left bank of the river basin Piomba, which flows just to the south of the study area with roughly NW-SE trend. Only the northernmost sector of the Reserve lies instead in the highest part of the small river basin Calvano. The gullies are a geomorphological phenomenon erosion caused by water, typical of the Mediterranean climate. For the formation of a gully are some necessary conditions: mainly clay soil but with a certain percentage of sand, slopes with high slope, but not excessive, exposure preferably south, thin soil and climate characterized by storms and dry seasons.

The clay is a ground formed from microscopic particles of lamellar form, which adhere to each other. When the clay is dry, the soil becomes dry and crumbly, with cracks and fissures on the surface; when wet becomes "plastic" and can be easily molded with the fingers. The minerals that compose contain few nutrients readily used by plants that take root with difficulty.

On a dry clay soil and cracked, the violent impact of the water drops of a storm causes the disintegration of small particles of earth; if the slope is high enough the water flows quickly on the surface and in the cracks, removing additional particles and creating a series of gutters (runoff).

If conditions are favorable, the rate of erosion is greater than that of soil formation (ie the formation of soil suitable to accommodate vegetation). The land is bare soil quickly, the rivulets s'ingrandiscono and deepen (erosion ditches), increasing in number up to draw a dense river network in miniature, with steep valleys from the sides where the erosion of the bottom is faster the lateral (ravine).

The clay eroded by water particles, which are smaller and lighter, accumulate at the base of the ravine, and are transported by rivers to the sea. The top of the ravine, however, the slope is so high that the clay soil can not be stable: small landslides come off continuously, causing the retreat of the gully to the summit of the hill.