Google Earth may be a toy for most of the world, but it is transforming archaeology. It seems like every other piece of archaeological news I read these days is based on using satellite images to find archaeological sites. The latest is this Nature News piece about Maya agriculture. By combining field sampling with a lot of satellite study, archaeologists have been mapping the extent of Maya agriculture in wetland areas. We have known since the 1970s that the Maya turned some swamps into fields by digging canals and piling the muck on the adjacent plots. We did not know how extensive this process was, but now we know it was very extensive and probably provided a majority of the food for the Maya cities.
What intrigues me about this mapping it that the largest areas of wet fields were not near the major cities. (Kings and nobles hate to live in swamps.) Perhaps this contributed to the unceasing warfare of Maya times: if such a vital resource was not in the defensible heartlands of the major states, an enemy's temptation to conquer them or steal the crops or just burn the fields would be very great.