According to Archibald Sayce, the primitive pictograms of the early Sumerian (i.e. Uruk) era suggest that "Stone was scarce, but was already cut into blocks and seals. Brick was the ordinary building material, and with it cities, forts, temples and houses were constructed. The city was provided with towers and stood on an artificial platform; the house also had a tower-like appearance. It was provided with a door which turned on a hinge, and could be opened with a sort of key; the city gate was on a larger scale, and seems to have been double. The foundation stones — or rather bricks — of a house were consecrated by certain objects that were deposited under them."

What does Archibald Sayce think early Sumerian pictograms suggest about the availability of stone?