P.V. Heinrich’s Comments on Rockwall specimen

The following is an excerpt from a personal communication I received from Paul V. Heinrich after having sent him a fragment of the Rockwall stone and mortar. Note well his comments on the igneous vs. sedimentary origin of the stone. Other exchanges in the ’90’s between geologists Shelton and McKinney discuss the possibility of this being a hydrothermal sill or dike. I will have more to say on that possibility and others at a later time. The following was posted on the old Anarchaeology.com forum in 2005.

The following is an excerpt from a communication with Paul Heinrich, a geologist at LSU regarding some samples of the Rockwall stone and mortar material.

I have had one thin section made from the sample that you
sent and acquired another sample. One very intersting
aspect of the sample is its laminations it exhibited in hand
specimen. The thin section showed a well sorted, fine-grained
quartz and feldspar sand with heavy minerals with a well-
developed poikilotopic cement. This is a type of
calcite cement, in which the cement consists of single
crystals of calcite surrounding the sand. The optical
continuity of the calcite cement over large parts of the
thin section are quite striking. Although the term
“poikilotopic” is used normally for igneous and
metamorphic textures, poikilotopic calcite cement is
a sedimentary in origin and quite common in numerous
calcite-cemented sandstones.

It should be noted that in 1874, Richard Burleson, the first geologist to examine the walls, thought they were an igneous formation extruded from below which did not extend above the surface. It was Dr. Robert T. Hill in 1901 who first proposed that the walls were sedimentary in origin and the results of processes which formed the Balcones Fault which he assumed ran through Rockwall. This assumption was refuted by Dr. John T. Lonsdale, Director of the Bureau of Economic Geology of the University of Texas, in January 13, 1959, when he published an article categorically stating that the Balcones Fault ran no further than Hill County. Further he added that the Mexia Fault which runs through Hunt County and east of Rockwall had no involvement in Rockwall or Collin Counties. The latter are the two counties which evidence the buried wall phenomena of Rockwall.


#1 Jeff on 05.24.12 at 6:16 pm

HI, just discovered your site–wish I had heard when your forum was up & running.

Jeff in Missouri

#2 DavidCampbell on 05.25.12 at 10:05 am

Jeff, thanks for visiting Anarchaeology.com. The old forum was archived and made read only due to numerous hacking and spam attacks. It was originally intended as a storage area for new material and correspondence between myself and others who had made significant discoveries “on the ground”. Several pages on the main website are the result of those exchanges. When I took in “refugees” from other forums, it soon began to devolve into the armchair archaeological discussions better handled elsewhere. My polite requests to “keep it in Texas” or at least North America unless specifically germane to Anarchaeology’s content caused many to depart to their homeland. It was taking up too much bandwidth and screening spammers and bots manually was becoming a full time occupation.

Anyone who has found something of interest or who want a more detailed answer to questions relating to Anarchaeology.com can still do so by providing a contact email here (and several have already). Again, I appreciate your interest.

Yours truly,
David Campbell

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