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Show Loadua nalu ea gponaea. No modern architect would think of building a city upon so frail a foundation foun-dation aa a sponge seems to be, and yet tb greatest city In tha world, London, Lon-don, baa no mora secur a basa. It la trus th sponges are petrified and aa hard aa flint, but the fact remains just Ihe same. Tbe statement, of course, requires a little explanation. Th flint that forma th auuelratum of London soil Is nothing but petrified sponges; If you examine th fossil spong, or flint, with a glass you can see th structure ot th animal. They ar In layers. In tha southeast of England tha flint Is round under th chalk beds, but la th Tbamea valley th water haa gradually grad-ually washed away th chalk and left the flint. "Aa bard aa flint," although perfectly correct, sound rather strange In the light of th abor facta. |