The Shearing Channel is the ancient divide between the continents of Tal'Dorei and Wildemount where once was a land bridge, which was destroyed by the catastrophic forces of the Calamity, leaving nothing but a broken landscape of jagged rock and winding rapids that is near impossible to cross. Many ships that have tried to cross have never been seen again; it is said that great monstrosities live beneath the ancient waves and devour any who seek to cross.
The Briarwoods proposed the construction of a new bridge across the Shearing Channel to create a much faster trade and communication route between the two continents. Seeker Assum Emring said the bridge would somehow connect to the edge of the Alabaster Sierras, which surround the city-state of Whitestone in the northeastern part of the continent of Tal'Dorei. The Briarwoods claimed that the de Rolo family, which had ruled Whitestone, had been discussing the construction of such a bridge, and that the Briarwoods were hoping to talk about pursuing it as a joint venture, when the de Rolos were wiped out by disease and left Whitestone to the Briarwoods.
However, the proposal, which would have had to overcome steep cliffs, heavy winds, and strong ocean currents, was never a serious one; it was merely an enticing ruse to secure an in-person meeting at which Sylas Briarwood could magically influence Sovereign Uriel Tal'Dorei III. (The Briarwoods even proposed naming it "the Uriel Bridge" to flatter him.) The ruse worked; Uriel instructed Seeker Assum to invite the Briarwoods to a feast in Emon celebrating the agreement to build the bridge, and Sylas used the opportunity to charm Uriel.
After Vox Machina removed the Briarwoods from power, Percival de Rolo suggested that discussions about the construction of the bridge could continue with the new leadership in Whitestone, to which Uriel replied that the kingdom would pursue that discussion with the powers of Wildemount.