Based on the image provided, at least 7 tributary glaciers that have joined to form the trunk glacier flowing toward the viewer. The tributary glaciers are visible in the upper left of the image, and they converge to form a single, larger glacier in the foreground.
- Looking at the front of the image, at least seven tributary glaciers have joined to form the trunk glacier.
- This is evident by the presence of seven medial moraines, which are ridges of debris formed at the junction of two glaciers.
- Each medial moraine represents a former tributary glacier that has merged with the trunk glacier.
- Medial moraines can be seen as dark, winding lines on the surface of the glacier.
- They are formed when the two glaciers have different speeds or compositions, causing the debris to accumulate at the junction.
- The trunk glacier in the image is flowing towards the viewer, and the medial moraines are oriented perpendicular to the flow direction.
- This suggests that the tributary glaciers merged with the trunk glacier from the sides.
- It is possible that more tributary glaciers have joined the trunk glacier from upstream, but these are obscured by the trunk glacier itself.
- Therefore, the minimum number of tributary glaciers that have joined to form the trunk glacier in the image is seven.