The highly oxidised nature of the upper parts of the unit suggests that the lake bed was subaerially exposed prior to the deposition of Unit 1b. This could also explain
the presence of carbonate in this unit. Even though uncertainties are comparatively large in this age range, an age of 110 ± 5 ka from Unit 1a contrasts with the 70e92 ka ages in the overlying Unit 1b,and thus implies a prolonged phase of soil formation separating
Unit 1a and 1b between ~95 and 110 ka.