C1119 To be Lost in an Oasis(1)

The entire surface of the basin was made up of extremely thick glass, just like the Underground Glass Sea of the Sahara Desert. Its center was slightly sunken down, like a concave lens, producing excellent light gathering effects on the Sunlight in the desert.

And the "sand" at the edge of the basin, which was not completely melted but was half lump and half granular