The Silver Pit's geology is glaciation in cross-section. During the last glacial maximum - the Devensian, ending around 11,700 years ago - much of northern Europe lay under ice sheets hundreds of metres thick. The pressure of all that ice forced meltwater to flow not over the surface but beneath the ice, in subglacial rivers running under enormous head pressure. Those rivers carved tunnel valleys: deep, narrow, often steep-sided channels in the bedrock. When the ice eventually retreated, the channels were left behind, sometimes filled with sediment, sometimes scoured clean. The Silver Pit may date partly or largely from the older Wolstonian glaciation as well. Either way, it survived because the lower-than-modern sea levels of the late Ice Age meant the area that is now southern North Sea seabed was dry land - Doggerland - and the Wash River flowed through it, keeping the valley free of periglacial deposits that might otherwise have buried it.

The Silver Pit was discovered, in the working sense, by trawler fishermen from the South Coast of England in the 19th century. The North Sea trawl fishery was at that point one of the world's largest extractive industries. Sailing smacks - heavy beam-trawlers, much like the Frank or the Genesta that wrecked themselves on the Withernsea coast - dragged their nets across hundreds of square miles of seabed in all weathers, and the men who worked them developed an intimate, name-based knowledge of every shoal and ridge and pit on the bottom. The Silver Pit, off the broad continental shelf grounds, was a winter prize: flatfish, especially soles, gathered in it in numbers that justified the long sail east from Lowestoft or Grimsby in cold months. The name - Silver Pit, or sometimes Silver Pits - first shows up in trawler logs and fishing charts of the period.

In 2002, geologists Phil Allen and Simon Stewart announced the discovery of a buried crater-like structure in the seabed northeast of the Silver Pit, and named it the Silverpit crater after its neighbour. They proposed it was an impact crater - a remnant of an asteroid or comet strike around 60 to 65 million years ago, around the end of the Cretaceous. The claim was electrifying and controversial. Some geologists agreed; others argued that the rim and central peak structure could be explained instead by salt tectonics, the slow upward squeeze of buried Permian salt domes through overlying rock. The debate has now run for over two decades. The crater - if crater it is - sits buried beneath later sediment and is visible only on seismic surveys. Whether it is a wound from space or a slow geological pucker, it carries the name of the trawlermen's pit, and the trawlermen of Grimsby and Hull would, in their time, have sailed right over it without knowing.

The Silver Pit lies on the threshold of Doggerland - the drowned plain that connected Britain to continental Europe until about 8,200 years ago, when post-glacial sea-level rise and a tsunami from the Storegga landslide finally submerged it. Mesolithic hunters lived on Doggerland: their flint tools and bones turn up occasionally in the nets of modern beam trawlers, brought up from the seabed alongside the soles. The Wash River that carved and maintained the Silver Pit was one of Doggerland's great drainages. Now the only people who visit are the crews of trawlers, gas-field standby vessels, and survey ships running seismic transects over the suspected crater. The pit is invisible from the surface. It exists only as a slow change in seabed depth, a quiet groove a hundred metres deep, full of fish, holding the geological signature of an ice sheet that vanished thousands of years before anyone was here to remember it.