Limestone + Conglomerate Correlation?

I've noticed a trend of finding conglomerate rock in the same vicinity as limestone, and am wondering if any geology nerds can chime in. I actually have a degree in geology, but haven't used it in almost 15 years, so I'm rusty...

Anyway, in the U.S. I can think of a few examples. In Rifle at the Project Wall, you can find conglomerate at the base of the cliff, which quickly turns to limestone. The same is true at the Virgin River Gorge in Arizona/Nevada as you approach up to the Planet Earth and Blasphemy Walls. In Kalymnos in Greece, much of the flanks of the island are conglomerate, and there's even one conglomerate crag, though the majority of the island is limestone. Lastly, in Spain in the Austurias region, which is a limestone mountain range, there can be conglomerate found at the base of many of the cliffs, again usually on the approaches before reaching the wall.  All of the limestones are very different from each other and in extremely different locales, but what's most interesting to me is that the conglomerate is not like what you'd find in Maple Canyon where it's smooth cobbles. Instead, many of the large cobbles tend to be very angular and in a much more coarse matrix, whereas the matrix at Maple Canyon is very fine, like sand.

Limestone tends to form in shallow, warm marine environments, whereas conglomerates are usually a more active environment, such as a river, alluvial fans, or beaches. So I guess I'm wondering if at all of these locations, was there some sort of active, conglomerate formation (a river leading into the ocean, or an active beach environment), that was then overtaken by the ocean, which would lead to the younger limestone formation above it, and does this tend to be in true in most limestone areas?

P.G. here; Conglomerates have several standard depositional environments two of which would generally put them next to limestone in the rock record. But the scenarios you are mentioning in particular are likely basal conglomerates. These are associated with marine transgression/regression. During marine transgression sequences you will find locations with conglomerates underlying the limestone. In marine regression sequences you will have locations with limestone underlying conglomerate sequences.

Also conglomerates with angular clasts are generally called Breccias, you can further call them sedimentary Breccias to distinguish them from breccias that are volcanic in origin. As you might infer, the more angular the clasts the more recent and proximal the unit is to its source area.

Your answer is site specific. But yes, in general, places that form limestone create an environment likely to form Conglomerates, or Breccia (Conglomerates being rounded and Breccia having more angular clasts).  They are both formed similarly. Through chemical and physical weathering which breaks down a source rock. Conglomerates are then ground into rounded shapes by water in streams/rivers or by action of waves whereas breccia is not. And here is where the relationship to limestone comes in. Conglomerates and breccia both get filled in with a smaller materials like sand, clay or volcanic ash and are bound together by a cement like quartz, calcite or you guessed it, a limestone.  These minerals precipitate down into the material below and over time form the Conglomerate or Breccia. So if you have a suitable matrix and conditions where limestone is then formed above it, you are likely to see it over time solidified into a Conglomerate or Breccia.