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Brown soil, brown earth
Boss
An upwards protrusion of a batholith. Some bosses may once have been the magma chambers
of volcanoes. Land’s End and Dartmoor are bosses that form apparently quite separate areas of rugged granite landscape. However, out of sight below them they are connected by the main batholith.
Botryoidal
The shape of a mineral that resembles a bunch of grapes,
for example, haematite – the crystals of which are often arranged in massive clumps, producing a surface covered with spherical bulges.
Breccia
Large angular fragments of rock (rubble) that have been cemented together. The term comes from the Italian for fragments of stone. The rubbly alluvial cones at the foot of a mountain front produce angular material of this kind. Broken pieces of lava in cinder cones can also become cemented together. This is called volcanic breccia.
In general, the gaps between
the stones are filled in with
smaller material, often of sand size. The fine material and the coarser fragments are then cemented together, often with calcium carbonate that was deposited on the surfaces of the particles as lime-rich water percolated naturally through the sediment as it formed.
For breccias to keep their sharp edges and corners, they must travel only a short distance. As a result, breccias are found close to the rocks from which they were made. (See also: Coarse-grained rocks.)
 Breccia – A rock made from large pieces of rubble.
 Botryoidal – This
is a distinctive kidney- shaped habit associated with iron ores.
Brown soil, brown earth
Moderately dark, brown soils found beneath oak and other trees that shed their leaves seasonally. They are part of the soil group called alfisols. (See also: Acid soil.)
Brown soils mainly form on clay rocks. Each year the deciduous trees lose their leaves, returning nutrients to the soil. As a result
of this recycling of nutrients, the humus is nearly neutral and no harmful acids are produced. In turn, this means that the soil is suited
to a wide range of animal life, including earthworms. Earthworms pull humus into the soil and turn
over the upper levels of the soil, so that there is a good mixing of organic and mineral matter.
There is no sharp boundary between A horizon (topsoil) and B horizon (subsoil), as might be found, for example, in a podzol soil. Instead, there is a gradual change, known as a merging horizon.
Brown soils are used for crops and pasture, and form important farmlands in western Europe, the eastern United States, coastal Washington and British Columbia, as well as on South Island,
New Zealand.
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