Civil Engineering Reference
In-Depth Information
centred on the Atlantic Coast of Western Europe. It is a truly astonishing phe-
nomenon. In essentials the largest possible units of stone were procured weigh-
ing e.g. 30-40 tons. h ese could be furnished by natural processes of exfoliation,
or by levering away from i ssured bed rock. Two forms were utilised: great l at
slabs and pillars. With these were constructed artii cial caverns within a tumulus
of earth (dolmens), together with monumental standing stones (menhirs). Such
construction was current ca 4,500 BC-2,000 BC; and because of their massiveness
striking remains endure to this day of these monuments (R. Joussame,
Dolmens
for the Dead
; G. Daniel,
h e Megalith Builders of Western Europe
).
Megalithic construction is an enigmatic phenomenon both historically and geo-
graphically. At er ca 1500 BC it was never resorted to again in the Ancient World.
However in disparate regions outside the Ancient World (e.g. India, Korea, etc.)
where no connection by dif usion can be imagined megaliths occur at later dates
(R. Joussame,
Dolmens for the Dead
).
152
Extensive
knowl-
edge of
proper-
ties of
building
stones
153-157
56
B.
Varieties of Material
h e i rst concern in stone construction is the choice of material, since the variet-
ies of stone are very numerous. Field stones come in many shapes and sizes and
the physical composition of all stone is extremely diversii ed. h e physical nature
of any stone depends on its chemical components and the processes of its forma-
tion. h ese questions today constitute the sciences of lithology and petrology—the
i rst concerning the geology of rock outcrops, and the second the chemistry and
crystalography embodied in any item of stone. About these matters the ancients
had no knowledge. Nonetheless already in e.g. Old Kingdom times at the early
stages of large scale quarrying the Ancient Egyptians possessed close discrimina-
tion between the qualities of various stone outcrops; and organised expeditions
to quite remote localities to obtain supplies of specially suitable stone. h e close
knowledge ancient man possessed of all natural phenomena was obtained by long
sustained observation—by nature study rather than by science. Moreover man's
initial awareness of the qualities of stone pertinent to building was developed in
part by his prior familiarity with stone working in Neolithic times to produce
stone vessels and objects.
Certainly a very extensive knowledge of the physical varieties of stone is required
to build in stone to the best advantage. Stone is used for the widest variety of pur-
poses in building construction—to constitute the structure of a building in whole
or in part and to constitute its aspect in whole or in part. h us virtually every
physical type of stone imaginable is useful for some specii c purpose, and accord-
ingly virtually every physical type of stone has been used in building construction.
Furthermore from the beginning of i ne stone masonry (in the third millenium
