polymictic impact breccias?

I dont see any evidence . Why did you settle on impact breccias? IS the quartz shocked? remelting of old rock causes clasts to grt incorporated into the melt (anatectic breccias).

Are these rounded pebbles from a stream or alluvial plain that is near a possible impact arear?

Im puzzling why you jumped on calling it an impact breccia when there are so many other explanations that make more sense

I honestly didn't know that there were so many explanations for the origin of this kind of rocks. I try to be cautious. I know what you say has knowledge and accurateness. I would like to find something to refute my thinking or to corroborate it, because it is straining to be thinking about it and coming to no end. Sometimes I find the literature about impact cratering confusing, I've read that impact breccias can be mistreated by breccias of tectonic or volcanic origin, because they look the same, which have as a pattern, an apparent flow of exoliths. The Ries crater is an example that really shocked me, how could the rocks of this region be classified as volcanic in origin for so many decades? Although I know you are very right, there is a scant chance for the impact crater supposition to be right, maybe I am abusing of sticking to that possibility. I am starting to think that the answer may be skippering on the field but totally discernible in the books. I found a place where these kind of pebbles were lying, the place is an slope in a granitic mountain, these rocks seemed to me anomalous to the landscape. The place is very dry, there is no evidence of a stream, unless in recent times. I had spotted the rocks previously when searching for fossils, I focused on them because they were different.

What is the approximate geographic location where you found these things?

There had to be a goodly flow of water to abrade those rocks like that. Regoliths and colluvial piles are merely sub-round and stillretain much of their original angularity. SO there must have been streams that deposited those rocks.
You may be standing on the evidence and not seeing it.
We usually start with a very simple explanation and as more data appears , we modify em.
Most bolide craters were mapped as tectonic features until people started recognizzing impact breccias , impacted ground-water reservoirs, and , of course, stressed quartz layers (which needed to be inspected in thin section)
Im not surprised that several craters were mismapped in the earlier days. We didnt have much of the technology like quick computers so we could make detailed gravity anomaly maps or resistivity tomography.

Your gonna have to
1. Look at a good recent geologic map of the area and, if you have trouble reading it, get some help from an oil field geologist or a sedimentary strat teacher at a nearby college.

2. If evidence appears to support your initial hypothesis, then take a rock to the college and see if they wont make a thin section and see whether theres any deeper evidence of an impact breccia.
Just try not to jump to a conclusion with such scant evidence

I may be stating the obvious here, but you're also going to have to convince yourself that those rocks weren't transported there from some other place (by human activity). Make sure there was not construction activity (current or ancient) that might have left those stones there.

Im giving him creedit for knowing a natural deposition of rounded rocks v a human engineered deposit. Usually , in an alluvial sediment deposition there are all kinds of different source rocks, the kind that are bounced about the stream bed till they come to rest at a point that the streams energy is no longer able to keep them moving. AT these same spots , heavy minerals and small grains deposit in between these bigger clasts and we have a gravel/sand deposit that covers a mappable areal distance.

If hes mde such a mistake then its time to go out in the field nd make sure .

I went back to the site to have a better insight. I noticed the stones were distributed in a range of 5 to 10 m2. There was human activity in the past, a railway is adjacent to the stones. There are stones in one side of the railroad but not in the other, suspicious. Then, I observed a gutter beneath the railroad, water carved 1 to 2 m in the soil exposing it, I would expect to see rounded rocks or sand to be visible, but instead, I saw the obvious, granitic grus and red clay. I focused in the gutter, I thought it was recent, but when I closed to it from one side I saw the date imprinted, 1913. I realized that these rocks were likely brought by humans and used as gravel in the construction of the gutter, I presume this kind of gravel was used in 1910s. At that time the company committed to financially support the construction of the railroad, underwent hardships, how far did they go to get these rocks? I don't know if it arrived in train or other mean of transportation. I would like to know where is the source of these rocks. I had found previously a brachiopod fossil in one of these rocks. Are these rocks from a shore or coast? It seemed to me that fragments of gneiss are incrusted in some of these rocks. Even I think they are fossiliferous, but I am not sure. It is interesting the fact after 100 years the stones are exposed like the day they were left over its resting place.

http://www.flickr.com/photos/51986587@N04/sets/72157634529241459/