You well expressed the Bay of Fundy situation.
The water rising and falling once during your mythical Flud would have left a little silt behind. A little, that is, in the spots where it was 15 cubits deep. Quite a bit, though, in the places where it was deeper. Like all the silt off the high places......
Setting aside considerations of the massive impact on land based life...
My vision of the flood impact:
Heavy rains for 40 days and 40 nights would cause massive erosion. All the finer sediments would be stripped off and carried to the land/ocean margins of the time, to form massive deltas. The coarser sediments such as boulders might be left behind as lag deposits.
Beyond that, I don't envision much sediment deposition. As the waters rose, significant sediment WOULD NOT be brought back to be deposited at higher elevations. And what little that was deposited would tend to be eroded back off post-flood.
So, post flood, I'd expect to see a lot of barren bedrock with massive delta deposits at the margins.
Moose