A good bottom may be formed by chalk rammed down close.
A naval battle was fought on the 5th of May 1864, in which the double-ender "Sassacus" most gallantly rammed the "Albemarle" and was disabled alongside her, and Smith's vessel and others, unarmoured as they were, fought the ram at close quarters.
Such stones may be of any size subject to each of them covering only a small proportion of the width of the structure (in the Vyrnwy dam they reached 8 or 10 tons each), and the spaces between them, where large enough, must be similarly built in with smaller, but always the largest possible, stones; spaces too small for this treatment must be filled and rammed with concrete.
The threshing-floor must be smooth and rammed hard to leave no crevices for weeds and small animals to get through.
Tabiya or rammed concrete of red earth and stone is the almost universal building material, and the houses are consequently seldom more than two storeys in height.