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The soil in Madeira is of volcanic origin, consisting mainly of basalt, trachytes and trachydolerites, tufa, scoria (clinker) and conglomerates.
Over time, the volcanic rock disintegrates under the erosion of sun and rain and produces a variety of soils. In general terms, these soils are clayey, acid, rich in organic material, magnesium and iron, poor in potassium and adequate in phosphorus.

Basalt predominates at lower altitudes, and is the origin of more or less clayey dark or reddish-brown soils. Trachytes are grey or dark-grey rocks found above 300 metres. Trachydolerites are lighter coloured and are found at very high altitudes. Tufa is solidified volcanic mud and occurs in two forms: pedra mole, which is yellow, and cantaria de forno, which is red. They have a variable composition. Scoria is solidified cellular lava, dark (sometimes purple) in colour, and porous in texture. Conglomerates are formed from basalt and tufa detritus.

 


Photograph by Henrique Freitas and João Freitas

 

 

 

From these basic geological types are derived various mixtures of soil, which have been classified into sub-types using regional names:

 

 
 
Massapez heavy clayey earth that does not drain water and cracks when dry
Salã a reddish clay similar to Massapez
Terra Grossa a heavy mixture of clay and grit
Pedra Mole a mixture of yellow clay and grit
Meia Terra a red and yellow medium soil.
Poeira a fine, dusty red and yellow soil found in the highest,coldest areas
Delgada a very gritty soil, rich in organic material
Solta a mixture of white clay and grit, rich in organic matter sandy soil
Areão sandy soil