Are you saying I need to take a direct sample of the conglomerate itself? There is a stream that runs out of that mountain probably not even 1/4 mile below that cut. The area is National Forest and that road isn't new.
Yes, you should also sample the contact layers top and bottom and make a log of your results. The more information you have, the better. It depends a bit on the road itself. Sometimes the road is just a little quarter section blasted out with the road constructed from the blasted material. So the top of the blasted rock is generally the deepest material, the bottom of the pile is the surface material generally. You can often see exactly where the layers begin and learn more about the deposit's shape and distribution.
I would take multiple samples of the conglomerate from different levels and from the rubble and do some basic processing experiments. As Allen mentioned, you could swing your detector over it to see if you can identify any larger gold. If there isn't any gold in it, then off to the next prospect.
I assume you guys in the states have similar rules where you cannot mine or prospect in national parks but "National Forest" is fair game I think, depending on the state. Depending on how old and remote the road is it will probably influence the chance to find something easy. There are "easy" small deposits all over the place but they still require a lot of effort to prospect. If a road is 200 years old, it means a lot of boots have walked down it over the years so a chance of discovery is lower unless it is out of the way.
What gets me excited are things like this:
Where an area is logged for the first time and the blasted road areas represent the first true decent sub surface look - meaning you could be the first person ever to pick up one of those rocks and care what they are. The loggers and road blasters care about wood and roads respectively, not the rocks beneath their feet.
911 follows the forestry companies and get logging road access keys from them - a very smart strategy in my opinion.