11.   Over aeons, the undulating plains have been showered by volcanic ash blown westward from Ngorongoro, Lemagrut and other now-extinct volcanos.

12.   Pozzolana is a volcanic ash, available in quantity in Italy, containing alumina and silica, which combines chemically with lime to produce a hard, durable substance.

13.   Recent volcanic rocks, including extensive sheets of volcanic ash, are predominantly acidic and intermediate in composition since the magmas have risen through continental crust.

14.   Bentonite is a clay formed from the decomposition of volcanic ash.

15.   But in the Goreme area, the volcanic ash that formed the tufa has proven stronger, and as a result cave life here never died out.

16.   Dust knows no borders, and dust from volcanic ash lingers in the upper atmosphere to produce brilliant sunsets thousands of miles away from the eruption.

17.   Dr. Craig Feibel, a Rutgers geologist, collected samples of volcanic ash for use in dating the material.

18.   Herman analyzes ozone, smoke, dust, volcanic ash and pollution from data collected by a NASA satellite.

19.   Made from cane sugar grown in volcanic ash, they are not refined down to white sugar, so they retain much of their natural molasses.

20.   Most unusual of all, they created the fairy chimneys, tall cones of tufa and volcanic ash that are topped by protective slabs of hard basalt.