What type of coastal deposits developed during the early Devonian seas transgression across the United States?

• A. Desert dune sands
• B. Glacial till
• C. Eolian dunes
• D. Thick deep-water limestone sequences

Answer: (D)

When a sea transgression occurs, sea level rises relative to the land and shoreline moves landward, expanding the marine environment over previously exposed areas. In warm, carbonate-dominated seas like those that covered much of North America in the early Devonian, this favors the widespread accumulation of carbonate minerals and skeletal remains, leading to thick sequences of limestone formed on the continental shelf and in deeper marine settings. So, during the Devonian transgression across the United States, the dominant coastal deposits were limestone-rich rocks deposited in deeper-water carbonate environments, rather than desert dunes, eolian sands, or glacial deposits.