Re: What is a terrace?

The "Dictionary of Geological Terms" by Bates and Jackson gives the following definitions for a terrace:

1. A relatively level bench or steplike surface breaking the continuity of a slope. The term is applied to both the lower or front slope (the riser) and the flat surface (the tread).
2. stream terrace
3. marine terrace
4. structural terrace
5. A horizontal embankment along the contour of a hillside, built to conserve moisture or reduce erosion.

Below we see a couple of schematic diagrams of terraces. The first one is just a diagram of the first definition above. We think of hills as being smooth going up or down, but as we see on the right-hand side, there is a section that is level. This is the terrace. Terraces can form for many reasons: differential erosion (one layer of rock erodes easily, but the one that is the terrace does not), stream incisement (2 above), and many other reasons.

The second one shows an example of stream terraces. These occur due to erosion by a river on its floodplain. Terraces that are above the current level of the river are the locations of river at an earlier time. The river continued to incise itself leaving the terraces as remnants of its earlier elevation.

1.)

2.)