Sand-ridge migration in St. Andrew Bay, Florida

摘要: Abstract This report presents the results of an investigation into nature a series remarkably uniform sediment ridges found on bottom St. Andrew Bay, Florida. Scientific divers from U. S. Navy Mine Defense Laboratory measured ridges, obtained samples, monitored their movement for period over 2 years, and installed current meter in order to record flow responsible movement. It was that were oriented normal composed fine-grained quartz sand. They exhibited heights 30–60 cm, wavelengths 13–20 m, migrating area bay previously characterized as mud. During 849-day investigation, one advanced total 11.44 m. The migration rate vary periodically response tides, being greater than average during periods when moon sun near maximum declination, smaller usual they celestial equator. Also detected gradual increase ridge-migration speed apparently related decrease ridge height long-term speed.