These township, range and section markers are often set above ground. Used to see them all over the southern California desert too. The pipe is about four feet long and they were pounded in as far as the surveyors felt like pounding.
The post is installed in sand of unknown depth atop bedrock. I seriously doubt that ten inches (25cm) of sandstone has been eroded in 70 years. The post probably always protruded from the ground as this one does:http://www.pbase.com/listorama/image/60364836 .
