Supports· moderateYDIH-E006
Wittke et al. 2013: ten million tonnes of spherules on four continents
- what the source states
- Analyses of boundary sediments at 18 sites on four continents reported abundance peaks in silica- and iron-rich microspherules whose geochemistry and morphology the authors interpreted as melt products of a cosmic impact event, estimating ~10 million tonnes of spherules deposited across ~50 million km².
- what we infer
- The proponents' widest observational claim — the hypothesis's footprint at maximum extent. Its force depends entirely on identification criteria and boundary dating that independent workers dispute; the tonnage estimate compounds every upstream uncertainty.
- limitations
- Proponent-team study; sites and horizons selected and identified by the same investigators whose earlier results were under challenge.
- No blinded identification; the 2016 blind test later found no standard criteria exist for these objects.