In the great mosque (1.9.7) there are red and white stone wedges that make up the series of repeating arches that dominate the interior. what are these stone wedges called?

These stone wedges are called voussoirs. 
Voussoirs are wedges, a type of stone often used for making arches and vaults - in this case, voussoirs were used to create arches in the Great Mosque (possibly referring to the Greate Mosque of Mecca, in Saudi Arabia). 

Photography has changed its subject matter quite a lot over the past few years. in the 1800's, it was considered normal for families to have  post mortem photos of their loved ones, and now that would be completely unacceptable. i think that photographers have always pushed boundaries and have been eager to capture everything, it is just society that changes their boundaries.

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