* Pebble conglomerate: This rock type is formed from large, rounded pebbles, indicating high energy environments like near-shore beaches or riverbeds.

* Quartz sandstone: This rock type is formed from sand-sized quartz grains, also indicating a relatively high-energy environment, but potentially further from shore than conglomerates.

* Shell limestone: This rock type forms from the accumulation of shells, indicating a marine environment with abundant life. While it can form in relatively shallow waters, it's not the furthest from shore.

* Silty shale: This fine-grained rock forms from the accumulation of mud and silt, indicating a low-energy, quiet environment like a deep ocean floor far from the shoreline.

Therefore, silty shale is the most likely to form farthest from the shoreline.