SUMMIT ANGLE OF REPOSE SLIPFACE WINDWARD ANGLE OF REPOSE FOC 34°
All dunes may be described by the above traits. Variations in shape and size of individual dunes are determined by the mathematical values applied to each of the traits mentioned in the discussion of ripple formation. Another feature of interest is the dune shape. Among these dunes you may find examples of this classic textbook model and its variations.
Plants on the playa in between the dunes
Note that the downwind side of the dune, the slipface, is the steeper one. Fine dry sand can only pile up so high before it breaks away and slides down the slipface as an avalanche to rest at the more stable angle of repose, about 34 degrees. We create miniature avalanches as we walk along the crest of a steep dune.
WHAT PLANTS LIVE HERE?
Each area within the dunes has something different to offer. Low dunes near the picnic area have more vegetation than the tall dunes near Highway 190.
Plants, visible from the top of many dunes, help the dunes remain here by stabilizing the sand with their branches and roots. You will see different plants, depending on whether you are in the tall or low dunes. You may find them in a different sequence from that used in this booklet. By looking for different shades of green, you should find each of the major shrubs and trees that live in the dunes. Use the diagrams and photos to help identify those you see. Let’s take a closer look to learn how they survive and how they relate to the story of the dunes.
Can you find a low bush which appears to have no leaves? The stems are jointed and succulent (juicy) and vary in color from yellowish to bright green, depending on the season. Pickleweed (Allenrolfea occidentalis), is often found on top of low mounds of sand. Do the stems look like tiny pickles joined end-to-end? During summer months, tiny, inconspicuous, yellow flowers may be seen at the joints. With a magnifying glass, you may see the miniature leaves.
