Layers of lava, ash, scoria and pumice make up the volcanic peak. Volcanic ash and pumice blanketed the countryside. Scoria differs from pumice in being denser. Fine ash and pulverized pumice can deposit over large areas. Typical mixes include large-grade drainage material such as perlite, pumice, or ceramic balls. Burkina Faso's natural resources include gold, manganese, limestone, marble, phosphates, pumice, and salt. Loose pumice and ash deposits formed lahars down all the main rivers. It may have originated in the open country created by lava, volcanic ash, and pumice. The tent rocks are composed of soft pumice and tuff. Pyroclastic flows of hot pumice and ash along with dome growth occurred during this period. Submarine volcanoes erupt on the ocean floor and produce the extrusive rock pumice. The team excavated of deposits of pumice and ash. Scalping screens are used to filter impure surficial pumice of organic soils and unwanted rocks. A blanket of ash and larger pumice lapilli blanketed the countryside. This stage formed a large area of white comenditic pumice and ash.