What type of glacier ends in a valley that is filled by an arm of the sea?

A glacier that ends in a valley that is filled by an arm of the sea is known as a tidewater glacier. These types of glaciers terminate at the coast, where they can calve into the ocean, producing icebergs. This specific interaction between the glacier and marine environment is what defines tidewater glaciers, as they are subject to both glacial processes and oceanic conditions.

Tidewater glaciers are typically found in regions where the coastal terrain allows for glaciers to flow down from the mountains into the sea, often creating stunning landscapes where the ice meets water. The melting process in these environments is influenced by warmer sea temperatures, which can accelerate calving and impact the glacier's mass balance.

In contrast, alpine glaciers are found in mountainous regions and flow down valleys, but they do not necessarily terminate in bodies of water like tidewater glaciers. Piedmont glaciers spread out over a broad area at the base of mountains but are not specifically associated with sea arm terminations. Ice sheets are vast, continental-scale glaciers that cover large areas but do not end directly at the sea in a valley context, as tidewater glaciers do.