mantle

1. Chemistry a small dome-shaped or cylindrical mesh impregnated with cerium or thorium nitrates, used to increase illumination in a gas or oil lamp

2. Zoology

a. a protective layer of epidermis in molluscs that secretes a substance forming the shell

b. a similar structure in brachiopods

3. Ornithol the feathers of the folded wings and back, esp when these are of a different colour from the remaining feathers

4. Geology the part of the earth between the crust and the core, accounting for more than 82% of the earth's volume (but only 68% of its mass) and thought to be composed largely of peridotite

5. a less common spelling of mantel

6. Anatomy another word for pallium

7. a clay mould formed around a wax model which is subsequently melted out

Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

mantle

The zone within a planet or satellite, lying below the crust. See also Earth.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006

mantle

[′mant·əl]

(anatomy)

Collectively, the convolutions, corpus callosum, and fornix of the brain.

(biology)

An enveloping layer, as the external body wall lining the shell of many invertebrates, or the external meristematic layers in a stem apex.

(engineering)

A lacelike hood or envelope (sack) of refractory material which, when positioned over a flame and heated to incandescence, gives light.

(geology)

The intermediate shell zone of the earth below the crust and above the core (to a depth of 2160 miles or 3480 kilometers).

(metallurgy)

That part of the outer wall and casing of a blast furnace located above the hearth.

(vertebrate zoology)

The back and wing plumage of a bird if distinguished from the rest of the plumage by a uniform color.

mantle

1. Same as mantel. 2. The outer covering of a wall which differs from the material of the inner surface.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Mantle

one of the shells of the earth that lies directly under the earth’s crust. The mantle is isolated from the crust by the Mohorovičić discontinuity, which is found under the continents at a depth of 20 to 80 km (on the average, 35 km) and under the oceans at a depth of 11 to 15 km below the water’s surface. The distribution speed of seismic waves (used as an oblique means of studying the internal structure of the earth), upon crossing from the crust to the mantle, increases abruptly from about 7 to 8 km per sec. The base of the mantle is believed to lie at a depth of 900 km (where the mantle is divided into upper and lower parts) or at a depth of 400 km (where it is divided into upper, middle, and lower parts). The zone between 400 and 900 km deep is called the Golitsyn layer.

The mantle is probably made of granite peridotites, with mixtures in the upper parts of eclogites. An important characteristic of the structure of the mantle is the presence of a zone of reduced seismic wave speed. There are differences in the structure of the mantle under the different tectonic zones—for example, under geosynclines and platforms. Processes develop in the mantle that are the sources of tectonic, magmatic, and metamorphic phenomena in the earth’s crust. The mantle is accorded an important role in many tectonic hypotheses. For example, it has been suggested that the earth’s crust was formed by a process of smelting from the substance of the mantle and that tectonic movements are connected with movements in the mantle.

REFERENCES

Magnitskii, V. A. Vnutrennee stroenie i fizika Zemli. Moscow, 1965.
Belousov, V. V. Zemnaia kora i verkhniaia mantiia materikov. Moscow, 1966.
Belousov, V. V. Zemnaia kora i verkhniaia mantiia okeanov. Moscow, 1968.

V. V. BELOUSOV

Mantle

(in biology). (1) A fold in the skin of certain invertebrate animals (mollusks, brachiopods, and barnacles) that encloses the body of the animal completely or in part.

In most cases the external skeleton of the animal is secreted by the mantle. Between the body and the mantle is the mantle cavity, which is connected to the outside environment and into which the kidneys, sexual glands, and rectum open. In the mantle cavity are the respiratory organs (gills) and certain sense organs. In aquatic animals the mantle is usually lined with ciliated epithelium; the beating of the cilia creates a current of water through the mantle cavity. This current delivers oxygen and food particles and carries off metabolic products. In some gastropod mollusks there are networks of blood vessels in the walls of the mantle, forming a kind of “lung.” In cephalopod mollusks the mantle is muscular and is used to expel a stream of water through a special funnel, giving the animal jet propulsion.

(2) The mantle, or tunica, is part of the formative tissue (meristem) in the growing point (apex) of the stem of plants. The inner layers of mantle cells divide both perpendicularly to the surface of the apex, that is, anticlinally, and parallel to the surface of the apex, that is, periclinally (in this case the inner part of the apical cells is called the corpus). Subsequently, the epidermis and primary cortex differentiate from the mantle, and the axis cylinder differentiates from the corpus.