black sea
Mediterranean Sea
black sea
antic
The Gulf Stream.
The Ohio River
The Atlantic Ocean forms the state's eastern boundary.
The Rio Grande
The Atlantic Ocean.
The boundary between Europe and Western Russia is the westernmost boundary of Russia, bordering countries such as Finland, Poland, and Belarus. If you meant what is the boundary between European Russia (Western Russia) and Asian Russia (Eastern Russia), it is the Ural Mountains.
The Red River (of the North) forms North Dakota's eastern boundary with Minnesota.
because the molten rock cools in the water and forms a oceanic crust