metallurgy was just starting to move up into northern chijuajua at that time and they were working with copper. that was just ornamental, so there was no metal going on at all other than imported bells. >> and the shells, they went down to cortez -- not lake -- the cortez sea to get, was that mostly hard or brittle? . >> it was hard but not tool hard. the colorado plateau is covered with chert, a glassy rock that is really really good for making tools, making very sharp edges. you find there are pieces of chert all over the place and you can still cut your skin open very quickly with it and it's been sitting out in the open. >> where does chert come from? . >> it's a marine rock that's mostly silica. you find it in these layers, sandstone layers. if you are especially in a marine or water environment, you will find this layer of chert. it's in all colors, purple, green, red, blue. it's a beautiful rock. . >> one thing i wanted to ask you, the review in the paper recently on sunday said that your book is different from all the other books about the anastazi because you brought out some o

from the four corners region from arizona, new mexico, colorado and california meet down to the chijuajua area of new mexico. there was one excavation along the way i remember out in the desert nears winslow, arizona. the desert out there is just a still life with a few landmarks on the horizon and this empty hole, the little colorado river desert, the painted desert, and we were working on a 500-room pueblo dating back to about 1400 ad. i just remember the wind just hailing down on us for days and you would be working down with trowels inside of a trench and if you stop for too long, the sand would start to fill up your hole again because it was blowing so much and everybody was turned away from the wind. so it looked like some kind of religious thing was going on here, all these people bowed to the ground for days and days tinkering with some unimaginable smallness in front of them while the wind just pushed harder and harder, sand blasting across you, filling up all the rooms that you just emptied out as if the desert is rolling back over itself. because even where trails are left, tra