Kentland crater

The Kentland structure, also known as the Kentland crater or the Kentland disturbed area, is an impact structure located near the town of Kentland in Newton County, Indiana, United States.

It was discovered about 1880 when two farmers began to quarry crushed rock there. The presence of shatter cones and deformed bedrock led geologists to conclude by the late 1960s that the Kentland structure is an deeply eroded impact structure, rather than volcanic in origin. Deformation at the site is so great that vertical contacts between normally horizontal rock formations of different ages are common.

The structure itself is a circular dome, about 7.24 km (4.50 mi) in diameter, deeply eroded and buried in glacial debris. Its age is estimated to be less than 97 million years (Cretaceous or younger). The Shakopee dolomite at the center of the structure is about 450 million years old (Ordovician period) and is uplifted about 2,000 feet higher than the level of the same rock in the surrounding area. The entire disturbed area is about 13 km (8.1 mi) in diameter.

The estimated age is in dispute.

This impact structure was studied in 1978. John Weber and his associates presented fission track dating of apatite from this impact structure.Coesite and shatter cones are found in the uplift near its center. The impact structure is exposed to the surface, resulting in erosion. It is currently being worked as a quarry.

The impact site is located 4 kilometres (2.5 mi) east of Kentland, Indiana in Newton County. The disturbance is 12.5 kilometres (7.8 mi) in diameter. The bedrock has a thin layer of glacial till, with a maximum depth of 40 metres (130 ft) in the depression ring. The bedrock around the impact structure is generally flat with a slight dip towards the southwest and the Illinois Basin. The upper layers are Lower Mississippian from the Carboniferous period and Upper Devonian are relatively flat throughout this area of Indiana with the exception of impact site.

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