The conversion from platey to angular blocky structure has not progressed as deeply as the conversion from a grey soil matrix with red mottles to a yellowish brown matrix with strong brown mottles (cf.
Where cutans or mottles are very prominent in the B-horizon, their colour was used for an alternative colour classification.
It is, by and large, equivalent to the depth to which partial changes of non-matrix colours have progressed; cutans have partially changed from black to reddish brown, and mottles have changed from the original red to more yellow or brown (Munsell colour changes from 2.SYR to 5YR or 7.5YR, and even to 10YR) (Fig.
The position of this first restrictive layer coincides with the Btv4-horizon, which still has its original coarse (20-50 mm) platy structure, and a grey matrix with mostly red mottles, the mostly unaltered old `mottled zone' (for details see Brouwer and Fitzpatrick 2000, 2002 this issue).
Above this restrictive layer cutans have partially changed colour from black to reddish brown, and the mottles have changed from red to more yellow or brown (for details see Brouwer and Fitzpatrick 2000, 2002 this issue).
The correlation coefficients for linear regressions in Table 2 indicate that the Bt-horizon redness rating of Hurst (1977); the matrix + mottles, and matrix + mottles + clay films indices of Mokma and Cremeens (1991); and the chroma + hue index of Evans and Franzmeier (1988), are more or less equally useful for the prediction of the duration of waterlogging at the bottom of the E-horizon.