Most likely the roof is a species of concrete. Most tract construction in the Southwest uses concrete roof tiles that are painted or dyed different colors. Terra cotta is too expensive for tract builders and there’s a lot of waste. Even the million dollar homes in my area use concrete over terra cotta. Look on the underside of the roof tiles. You’ll probably see that it’s gray.
You can usually walk on the “valleys”; you just have to be careful. You should be able to use a ladder for a lot of it.
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