Were they salt domes such as are common along the United States Gulf Coast, and if so, why should there have been so much solid crystalline salt beneath the floor of the Mediterranean?

它们是在美国墨西哥湾沿岸的那种很常见的盐丘吗？如果是的话，为什么地中海海底会有这么多坚硬的结晶盐呢？