The orientation of the continents at the time these limestones were being deposited. Virginia was located well south of the paleoequator at temperate to sub-tropical latitudes.
In the diagram above, there is a lot going on. First, note that all sedimentary layers are deposited oldest to youngest and in an originally flat/horizontal orientation. In from oldest to youngest with the oldest on the bottom, here is the order of deposition: Massanutten Sandstone - Far right of diagram - Similar to today's Virginia Beach, but still in water over your head! Cub Sandstone (Cub SS) - Shallowed significantly to nearshore, streams feeding sediment into the basin Upper and Middle Martinsburg - All carbonate gone and deep water submarine landslides (Bouma Sequences) Lower Martinsburg - Deepest water - below all wave bases, begin mixing in material eroding from land Edinburg Formation - Still deeper, but still on the continental shelf Lincolnshire Formation - Deeper yet - between normal and storm wave base New Market Formation - Like wading in a bit deeper Beekmantown Formation - Like wading in on the Caribbean beach to water just over your head Conococheague Formation - Similar to a shallow white carbonate beach in today's Caribbean, except the only life on land is algal. The sequence of layers above is a typical "Highstand Systems Tract", a sea level cycle that begins with sea level at a low ebb. Relative sea level then rises until a point of "highstand" (deepest), after which it regresses and ends in a "sequence boundary". The top of this sequence boundary is formed after the Taconian Mountains are formed and have largely eroded away by the middle of the Devonian Period.Stromatolites-hamel... Gs _0639