Final answer:
A terminal moraine indicates that the glacier's budget was balanced or that accumulation outpaced ablation at the time of its formation, suggesting a period of stability or advancement for the glacier. The presence of these moraines reflects the substantial growth of glaciers during the Little Ice Age, which has reversed into a trend of retreat due to climatic warming.
Step-by-step explanation:
The terminal moraine of Teton Glacier in Grand Teton National Park signifies the previous reach and mass balance of the glacier. When a glacier develops a terminal moraine, it indicates a period in which the glacier's front, or terminus, was relatively stable or advancing, as it deposited debris at its edge. At the time of the terminal moraine's formation, it suggests that the glacier's budget was relatively balanced or that accumulation (snowfall) was greater than or equal to ablation (melting and sublimation), allowing the glacier to push forward and deposit morainal material.
Such landforms, in conjunction with historical data, show that glaciers in the region experienced substantial growth during the Little Ice Age, which lasted until around 1850 AD. However, with a warming climate, the trends have shifted towards retreat, as glaciers continuously lose mass and decrease in size, which is reflected in the diminishing number of active glaciers observed in the park.