A revised age provided by conodonts from the Gilwern Oolite of the Clydach area of South Wales allows a clearer understanding of the palaeohydrology, palaeoclimatic history and diagenesis of previously correlated oolitic units. Earlier uncertainty over the apparent sub-regional differences in climate during the early Visean (Chadian—Arundian) lowstand is resolved. Previously a humid interval evidenced by prominent palaeo-epikarst capping the Gilwern Oolite along the northern outcrops of the South Wales synclinorium, was not recognized in what were regarded as correlative outcrops in the Chadian Gully Oolite in the southern part of the synclinorium. Conodont dating now shows that the Gilwern Oolite is much older (Courceyan) than the Chadian Gully Oolite, and during the prolonged exposure of the former there was an interval of weathering under a humid climate. This also explains the contrast between the diagenesis seen between the Gilwern and Gully oolites, which are no longer seen as correlatives.

来自南威尔士克莱达克地区吉尔韦恩软质岩的牙形石提供的年龄修订，使人们对以前相关的橄榄岩单元的古水文学，古气候史和成岩作用有了更清晰的认识。解决了早期Visean（乍得-阿伦迪亚）低水位期次区域气候明显差异的不确定性。以前，在南威尔士斜斜角北部露头上盖着吉尔韦恩橄榄岩的明显的古表观喀斯特溶蚀带证实了一个潮湿的间隔，但在斜斜角南部Chadian Gully Oolite的相关露头中并没有认识到这种湿润间隔。现在，牙形齿的约会表明，吉尔韦恩（Gilwern）橄榄石比乍得（Chadian）沟壑（Goully Oolite）年龄大得多，在前者长时间暴露期间，在潮湿气候下会有一定的风化间隔。这也解释了在Gilwern和Gully橄榄岩之间发现的成岩作用之间的对比，后者不再被认为是相关的。