 Gilbert had assumed that if it were an impact crater then the volume of the crater, as well as meteoritic material, should be present on the rim.Gilbert also assumed a large portion of the meteorite should be buried in the crater and that this would generate a large magnetic anomaly.Gilbert's calculations showed that the volume of the crater and the debris on the rim were roughly equivalent, so that the mass of the hypothetical impactor was missing, nor were there any magnetic anomalies.