A series of ancient underwater etchings has been uncovered near the jungle city of Manaus, following a drought in the Brazilian Amazon. The previously submerged images -- engraved on rocks and possibly up to 7,000 years old -- were reportedly discovered by a fisherman after the Rio Negro, a tributary of the Amazon river, fell to its lowest level in more than 100 years last month... Though water levels are now rising again, partly covering the apparently stone age etchings, local researchers photographed them before they began to disappear under the river's dark waters. Archaeologists who have studied the photographs...