They represent areas of equal pressure<em /><em /> because they are isobars.
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Answer:
Water in this area may have been leftover from ancient times when saline seas occupied the western U.S., and, also, as rainfall infiltrates downward into the ground, it can encounter rocks that contain highly soluble minerals, which turn the water saline.
between Europe and Asia (dividing Eurasia): along the Turkish Straits, the Caucasus and the Urals (historically also north of the Caucasus, along the Kuma–Manych Depression or along the Don River) between Asia and Africa (dividing Afro-Eurasia into Africa and Eurasia): at the Isthmus of Suez.
