21.   Not since Mount St. Helens went up in a violent blur of volcanic ash will the Puget Sound experience such a landscape-altering blast.

22.   Ofer Bar-Yosef, an anthropologist at Harvard University, says Japanese dating techniques using volcanic ash are usually reliable.

23.   Sections of specimens have revealed teeth, bones, seeds, leaves, stems, spores, fish scales, snail shells, and shards of volcanic ash.

24.   Shuttle astronauts used eight vials of dust samples, including one containing volcanic ash from Mount Shasta in Northern California, for the experiment.

25.   Since then, geologists sifting through volcanic ash at the discovery sites near Lake Turkana extracted enough crystals to conduct a more definitive argon dating analysis.

26.   The animals had walked over volcanic ash when it was damp from rain, leaving impressions of their feet.

27.   The beverage was fermented by sugars taken from the plant that grows only in soils rich in volcanic ash.

28.   The dating was done on grains of the mineral zircon found in trace amounts in volcanic ash.

29.   The difficulty surfaced soon after the mission began Friday, limiting the observations of clouds, dust and volcanic ash in the atmosphere.

30.   The houses unearthed from volcanic ash are real houses, the rutted streets are human scale.