Answer:
Deep ocean currents.
Explanation:
In cold regions, such as the North Atlantic Ocean, ocean water loses heat to the atmosphere and becomes cold and dense. When ocean water freezes, forming sea ice, salt is left behind causing surrounding seawater to become saltier and denser. Dense-cold-salty water sinks to the ocean bottom.
Well, this is surely not in the US. But the Garo, Khasi, and Jaintia Hills are all located in parts of Assam, India, and Meghalaya, India.