Possible structure excavated

This is an image of my first contact with the possible structure

The gravel bed is very thin and not constant like the dig on the opposite bank.

I did at first think it was a sandstone boulder crushed and split by geological pressures from above, but then found limestone included in the line of stone going into the clay bank.

It does appear to have maybe collapsed to this angle.

I have informed certain professional organisations of this excavation, and hope to get some feed back soon, i am worried about any damage that could be done due to flooding.

This could well be some geological phenomena i have not seen before, but it looks very much like it was built.

The line of stone does dissipate but still unmistakeably runs straight and deep into the lower clay deposit that sits above the gravel bed.