Beside the numerous scantily ornamented pottery vases, there were some decorated in coloured glazes with concentric lines, rosettes, and plaited bands (Fig. 152—_Frontispiece_). They come from the lower levels, which apparently date back to the time of the Assyrian domination. In one place where rubbish had been thrown, there were numerous tablets containing business, literary, or scientific inscriptions. It is possible that they came from the temple and formed part of the temple library, which, as is generally supposed, every temple possessed. No systematic storing of inscriptions has yet been discovered in any temple, including those of Babylon, Khorsabad, and Assur, all of which have been completely excavated. It is true that these were buried under a proportionately shallow covering of earth, while Esagila lay protected under fully 20 metres of untouched accumulations, and is still unexcavated. The mound itself proves to be thickly strewn throughout with potsherds, and the mud-brick walls of the houses lie close below the surface. They are only thinly covered by a uniform layer of dust. In the plain, on the contrary, as our trenches at the Ninib temple have shown, the house ruins lie under a layer more or less high, of drifted sand, and the surface contains exceedingly few potsherds. All this is explained if we take the trouble to realise the antecedents of the formation of these ruins. At the time when the site was deserted and fell into ruins the surrounding contours were far more marked than they are at present. The heights were higher and the depths were deeper. The mud-brick walls, which at first stood out above the soil, crumbled away after they lost their roofs into dusty heaps of clay, which accumulated against the walls and covered the pavement higher and higher, while the walls themselves, so far as they over-topped these heaps, disappeared, and thus all was levelled to an irregular undulating surface. [Illustration: FIG. 153.—Schematic diagram of the transfer of the upper levels (A, B, left) of a mound of debris to lower-lying region (A, B, on the right). ]