Dilute hydrofluoric acid leaching of radiolarian cherts has yielded th
e first identifiable radiolaria from the Northern Belt of the Southern
Uplands. The radiolaria are abundant, as are sponge spicules, and occ
ur with spindle-shape hollow biomorphs of unknown affinity. The red-br
own chert sequence at Hawkwood Burn may be correlated with the upper L
lanvirn (Llandeilian)-Caradoc Haplentactinia juncta - Inanigutta unica
assemblage in Nazarov's (1988) biozonation. The presence of Protocera
toiciskum sp. and the absence of typical Arenig morphotypes indicates
that the greenish-grey cherts near Crawford can also be tentatively re
garded as of Llanvirn-Caradoc age (sensu Fortey ed al. 1995).