1. The Width of a Day
2. Threads

a thread from chapter IV

The land bridge

Drain about 165 feet (50 m) of water from the Bering Strait and you can walk from Asia to America. For thousands of years, the sea did exactly that.

165 feetA shallow strait

The Bering Strait is only about 165 feet (50 m) deep at its shallowest crossing.¹ Lower the sea by that much and the strait is dry.

At the height of the last ice age, roughly 26,500 to 19,000 years ago, ice sheets held so much water that the global sea level stood about 400 feet (120 to 130 m) below today's.²

35,700 years agoLater than anyone thought

A 2022 study found that the land bridge appeared surprisingly late: only about 35,700 years ago, less than 10,000 years before the ice age peaked.² The exposed land, Beringia, was enormous, up to about 1,000 miles from north to south.³

The Diomedes would have stood as two high hills on that plain. That follows from the depths; no source we found says it directly.

11,000 years agoThe sea comes back

Sediment cores from the seafloor north of the strait show seawater first flowing through it about 11,000 years ago, later than several earlier estimates.¹ After that, Asia and America were separate again, with the Diomedes as islands in the gap.

debatedWho crossed, and when

Genetic studies suggest the ancestors of Native Americans may have lived in Beringia, cut off, for thousands of years before moving south. This is called the Beringian standstill.^4,5 It is a hypothesis: some researchers argue the long pause happened elsewhere, and the archaeology has not settled it.⁴

People were certainly in North America at least 14,500 years ago.⁴ Footprints at White Sands, New Mexico, dated in 2021 and confirmed by two more methods in 2023, suggest people were there 21,000 to 23,000 years ago, though some researchers still question it.⁶

So the question at the bottom of the Bering Strait is still open. What is not in doubt is the shape of it: for a long time, there was no strait at all.