... sediments have been recognized. The most important marker horizons are composed of porcelain-like silicified tuffs, limestones with inclusions of brown chalcedony, calcilutites, salt rock, wax-like bentonitic mudstones, flint clays, tripolis, etc. * Corresponding author. E-mail address: akulov...

...W. D. Keller Abstract Scanning electron micrographs show the textural differences in representative tripoli rocks from the three major tripoli-producing districts in the United States. Arkansas tripoli preserves the polygonal, triple-point texture of the parent metamorphic novaculite. Illinois...