It's over by Little Dumont.
Here ya go. I made a Google map with some markers on it. Zoom in or out to see exactly where it is in relation to the dunes.
<iframe width="640" height="480" frameborder="0" scrolling="no" marginheight="0" marginwidth="0" src="http://maps.google.com/maps/ms?msa=0&msid=216857937271360156497.0004ba8916f2aa8959590&ie=UTF8&t=h&ll=35.636267,-116.275821&spn=0.004177,0.006866&z=17&output=embed"></iframe><br /><small>View <a href="http://maps.google.com/maps/ms?msa=0&msid=216857937271360156497.0004ba8916f2aa8959590&ie=UTF8&t=h&ll=35.636267,-116.275821&spn=0.004177,0.006866&z=17&source=embed" style="color:#0000FF;text-align:left">Dumont Dunes</a> in a larger map</small>