Ogives (glaciers)

Ogives can be found on glaciers (usually advancing or neutral) and can be visually identified as light and dark bands occurring as ridges and valleys on the surface of glaciers. Ogives are created by icefalls, producing a pattern of alternating ridges and swales that gradually flatten out downglacier, and bend throughout the glacier in accordance to the greater velocity of the glacier being near the center. The only place an ogive can be created is at the base of these icefalls. As ice passes through an icefall it is usually badly broken up, which greatly increases the ablation surface area in the summer and providing space for enhanced entrapment of snow fall during the winter. The combination of both a dark and light band together can represent the annual movement of the glacier, suggesting that ogives are genetiacally linked to seasonal motion. WInter ice that passes through the icefall shows up bulgey/irregular/hummocky at the base of the icefall as opposed to summer time when it turns into a swale.

References

*Easterbrook, D.J. (1999) Surface processes and landforms. (Second Edition). Prentice Hall, Upper Saddle River, New Jersey.