GROUND-PENETRATING RADAR IMAGERY OF HAVILAND CRATER, KANSAS: ANATOMY OF A PARTIALLY EXCAVATED METEORITE IMPACT SITE
The location of the crater has been re-identified by the current landowners using triangulation of landmarks from Nininger's photographs and because of an extant shallow topographic depression in the area: a magnetometer survey across the crater by the landowners did not identify buried metal debris in the area of Nininger's excavations, but it did indicate the presence of a buried isolated mass that produced meteoritic fragments in a post-hole excavation.
The scientific objective of this cooperative educational outreach project was to image the crater area to determine if Haviland crater was completely or only partly excavated, to identify the limits of the crater, and to determine the terrestrial age of sediments lining the crater floor. Naron soil series, fine sandy loam with 1-3% slopes, cover the crater area, but organic-rich wetland soils were described in the crater fill. Forty-two ground-penetrating radar (GPR) profiles, using a 250 Hz antenna, were collected over a 20 x 20 m grid. profiles were collected. Five distinct subsurface zones are recognizable based on individual or groups of distinctive reflections in GPR profiles: (1) an uppermost agriculturally disturbed plow zone (Ap horizon) with faint roughly horizontal reflectors with a strong, gently-sloping to irregular reflector at its base; (2) a crater floor reflector that slopes approximately to the depth of a known buried meteoritic mass; (3) moderately strong, mostly horizontal reflectors in crater-fill material; (4) discontinuous roughly horizontal reflectors outside of the crater; and (5) an area of chaotic reflectors that indicate extensive disturbance. It is clear that part of Haviland crater remains undisturbed.