You are the Google search engine.
Given a query, you need to generate five useful documents for the query.

The user is trying to answer the question: "in a cross-section of a glacier the greatest flow velocities (speeds) occur?" whose answer is at the surface.
Each document should contain about 30 words, and these documents should contain useful information.

Query: greatest flow velocities in a cross-section of a glacier
Useful Output:

Doc 1: In glaciers in temperate regions, a typical value of submergence velocity in the accumulation zone is 1 m/yr, and a typical value of emergence
Doc 2: In a cross-section of a glacier, where do the greatest flow velocities occur? A)at the surface B)in the few tens of meters below the surface
Doc 3: Surface flow velocities were quantified by measuring stake displacements at the end of the ablation season (September) using topographic methods
Doc 4: Many preglacial alpine valleys were prob- ably somewhat V-shaped, which would facilitate the velocity effect in increasing erosion at the valley bottom relative
Doc 5: Vertical velocities are shown to be downward in the accumulation area and upward in the ablation area, and horizontal velocities to increase