Simplify the following text for a Grade 4 native English-speaking person.
Original: Marie Byrd Land is the portion of West Antarctica lying east of the Ross Ice Shelf and the Ross Sea and south of the Pacific Ocean , extending eastward approximately to a line between the head of the Ross Ice Shelf and Eights Coast .
Simplified: It is between the Ross Ice Shelf and the Ross Sea to the west and the Pacific Ocean to the north . It goes towards the east to a line between the head of the Ross Ice Shelf and Eights Coast .