Question: What is a large mountain massif in Antarctica that is 21 km long and 13 km wide and lies within the Sentinel Range of the Ellsworth Mountains, named after  a United States Representative from Georgia ?
Sentence (from "Jacobsen Valley"): Jacobsen Valley (Bulgarian: "долина Якобсен" , ‘Dolina Jacobsen’ \do-li-'na 'ya-kob-sen\) is the shallow valley in Vinson Massif, Sentinel Range in Ellsworth Mountains, descending northwards from the summit of Antarctica Mount Vinson (4892 m).
Relevant evidence: No