Lloyd DeKay on Dec. 2, 2023 at 2:40 pm said:
I suggest the flat tops of these clastic dikes are the result of an impenetrable layer atop the dike-bearing strata, which has subsequently been eroded away.
Lloyd DeKay – Webmaster for IAFI

My Masters Thesis was clastic dikes of the Panoche Hills (central) California.

And yes, the features seen in these photographs from Utah and seen in the recent issue of the Newsletter do look somewhat that they could be associated with clastic dikes. However, I would want to view them up close and personal before saying anything more. For one, the fracture system of the area is a strong clue as to their origins, something difficult to determine with the information at hand.

I don’t remember any of my dike structures being evenly truncated at their tops. Obviously at some point in their history there was significant erosion that planed the top of the structure off as well as the surrounding area; and the structures were durable enough to resist subsequent erosion and weathering enough so to persist, as we see them, to present. To make them as durable as they appear to be I would speculate that they were injected from below and into their existing cracks by sediment overlying a fluid rock unit (unconsolidated and wet sediment).

Norman Smyers3