Fig. 2 in New large-bodied mammals from the late Oligocene site of Chilga, Ethiopia

Fig. 2. Diagram of the Chilga stratigraphic section. The section has more than 90 m of volcanics at its base that are overlain by at least 130 m of fluvial and alluvial sediments. Stepwise alternating−field demagnetization was carried out on 118 samples with generally three samples per stratigraphic level. Paleomagnetic reversal stratigraphy demonstrates a dominance of normal polarity, and an 40Ar/39Ar age of 27.36 ± 0.11 Ma for a tuff in the upper portion of the sedimentary sequence at about 165 m provides an absolute tie point to Chron C9n (27.946−27.004 Ma). Small arrows to the far right of the geomagnetic polarity time scale of Cande and Kent (1995) represent "tiny wiggles," and the two brief reversal events within Chron 9 may be present at Chilga, providing additional but more indirect support for this correlation. Together these data suggest that this section is probably limited to the duration of this Chron (<1 Myr). Vertebrate−bearing horizons (V) occur primarily through the middle part of the section.