Boltysh
Key facts
- Country
- Ukraine
- Diameter
- 24 km
- Age
- about 65.4 million years
- Location
- 48.75° N, 32.17° E
Almost nothing: the crater is buried beneath younger sediments in the farmland of central Ukraine and is known from boreholes and geophysical surveys.
Boltysh is a buried impact crater in central Ukraine, in the Kirovohrad region. You cannot see it at the surface, where it lies beneath fields and villages. But it has attracted intense interest because of its age: it formed very soon after the Chicxulub impact that ended the age of the dinosaurs.
The impact. An asteroid struck the ancient crystalline rocks of the Ukrainian Shield, forming a crater about 24 km across. After the impact the crater filled with water, forming a lake that lasted for millions of years. Layers of sediment, including organic-rich oil shale, built up inside it and were later buried beneath younger deposits.
A close neighbour in time. Boltysh's age has been studied carefully. Early estimates placed it close to the end of the Cretaceous, raising the possibility that it was part of a series of impacts around that time. Some researchers suggested that it might even have formed shortly before Chicxulub. A precise study published in 2021 found an age of about 65.4 million years, roughly 650,000 years after Chicxulub. So Boltysh did not contribute to the mass extinction, but it formed while life was recovering from it.
A lake record of recovery. Because Boltysh's crater lake formed so soon after the mass extinction, its sediments preserve a record of how life and climate recovered in the early Palaeogene period. Fossil pollen and spores in the sediments show how plant communities changed. These records help scientists understand how ecosystems rebuilt themselves after the catastrophe.
Discovery. Boltysh was found during geological exploration in the Soviet era. Drilling for minerals and fuels revealed the buried crater and its impact rocks, including impact melt and breccias containing shocked minerals. The oil shales in the crater lake deposits attracted interest as a possible fuel source.
Why it matters. Boltysh shows that the Earth was not struck only once at the end of the Cretaceous. Several craters of roughly similar age are known, though precise dating has separated most of them from Chicxulub. Boltysh also shows the value of crater lakes as long-lasting archives of environmental change.
Seeing it today. There is nothing to see on the surface. The crater's story comes from drill cores, geophysical maps and laboratory analysis. Ukrainian geologists have studied it for decades, and international research teams have worked with them to drill new cores. Those cores show a thick sequence of lake sediments resting on impact breccia and melt rock, the whole story of the crater, from catastrophe to calm water, stacked layer upon layer.
Did you know?
Boltysh formed about 650,000 years after the Chicxulub impact.
Its old crater lake contains oil shale and a record of life's recovery after the dinosaurs' extinction.
The crater is completely buried beneath farmland.