an ice shelf is ice that has been compacted by snow and ice for hundereds of years forming its own land and are disapearing at an alarming rate because of global warming
Another Answer
An ice shelf is glacier ice that has flowed into the sea water over thousands of years and not melted. Ice shelfs float on the sea water, but can be hundreds of feet thick.
No one knows what exists under the Ross Ice Shelf, for example.
The Ross ice Shelf is a floating ice shelf connected to the Antarctic continent, that is about the size of France. The ocean under the shelf has never been explored.
The Filchner-Ronne ice shelf is attached to the Antarctic continent.
Any Antarctic ice shelf calves off sections into the Southern Ocean.
The land to which the Ross Ice Shelf is attached on three sides is the Antarctic continent.
The Antarctic continent is south of the Ronne Ice Shelf. All of the Antarctic continent is surrounded by the Southern Ocean. You can find the Weddell Sea north of the Ronne.
You can pick any two you want. From the Wikipedia entry: here is a list of the ice shelves, listed clockwise, starting in the West of East Antarctica. An ice sheet is included in the list: "Filchner Ice Shelf "Brunt Ice Shelf "Riiser-Larsen Ice Shelf "Quar Ice Shelf "Ekstrom Ice Shelf "Jelbart Ice Shelf "Fimbul Ice Shelf "Lazarev Ice Shelf "King Baudouin Ice Shelf "Hannan Ice Shelf "Zubchatyy Ice Shelf "Wyers Ice Shelf "Edward VIII Ice Shelf "Amery Ice Shelf "Publications Ice Shelf "West Ice Shelf "Shackleton Ice Shelf "Moscow University Ice Shelf "Voyeykov Ice Shelf "Cook Ice Shelf "Slava Ice Shelf "Gillett Ice Shelf "Nansen Ice Sheet "McMurdo Ice Shelf "Ross Ice Shelf "Swinburne Ice Shelf "Sulzberger Ice Shelf "Nickerson Ice Shelf "Getz Ice Shelf "Dotson Ice Shelf "Crosson Ice Shelf "Cosgrove Ice Shelf "Abbot Ice Shelf "Venable Ice Shelf "Stange Ice Shelf "Bach Ice Shelf "George VI Ice Shelf "Wilkins Ice Shelf "Wordie Ice Shelf "Jones Ice Shelf "Müller Ice Shelf "Prince Gustav Ice Shelf "Larsen Ice Shelf (Larsen A and B) "Ronne Ice Shelf"
The Ross Ice Shelf is a permanent part of the Antarctic continent, that rises to about 600 feet above sea level. The underside of the shelf remains largely unexplored. Its formation is continuous.
Berkner Island is a large island in Antarctica. It is surrounded by the Ronne Ice Shelf. The Ronne Ice Shelf is located between the Antarctic Peninsula and Queen Maud Land.
You may be thinking of the Ross Ice Shelf, which is about the size of France, or the Ronnie Larson Ice Shelf, which is decaying from underneath, because of warmer ocean waters around the Antarctic Peninsula.
Your question is really about ice shelves, not the Antarctic ice sheet. The ice shelves are deteriorating because of warmer ocean waters that melt the ice shelf from below.
According to the British Antarctic Survey:"The Ross Ice Shelf is the largest ice shelf of Antarctica (an area of roughly 487,000 square kilometres ((188,000 sq mi)) and about 800 kilometres (500 mi) across: about the size of France)."
The seaward side of the Filchner-Ronne ice shelf is divided into Eastern (Filchner) 79°00′S 40°00′W and the larger Western (Ronne) 78°30′S 61°00′W sections by Berkner Island. The whole ice shelf covers some 430,000 km², making it the second largest ice shelf in Antarctica, after the Ross Ice Shelf.