This is a subject about which there is dis-agreement. However, Norman Muller wanted me to add this.
Here is an explanation of what those curious weathered formations at the Miner farm and elsewhere are called. They are not geoglyphs but autoliths. Herman Bender provided me with the following explanation:
It took a bit of digging in my geology library, but I found it! The best term used to describe these rounded masses that weather out is : autolith - 1) an inclusion in an igneous rock to which it is genetically related Cf: xenolith, Synonym: Cognate Inclusion. 2) In a granitoid rock, an accumulation of Fe-Mg minerals of uncertain origin which may appear as round, oval or elongate segregation or clot. What it all means is that the 'round segegration' can be so close to the parent rock in lithology that it is barely indistinguishable and weathers out with Fe or iron present.
I as a geologist, have seen hundreds of these in nature and instinctively knew they were natural, a product of magmatic differentiation (i.e. an autholith) and in some other cases rheomorphic flow.