41. Progress below ground was slow, as a band of hard chert was encountered. 42. Mount Independence chert was traded across the Northeast. 43. Rock fragments in this are shales and cherts . 44. The m�lange was underplated beneath the chert layer. 45. In 1981, a neolithic axe-head made from greensand chert was found. 46. The red rock member is hematite stained chert . 47. The rocks of this sinkhole consist of Dartry Limestone, Knockmore Limestone and chert . 48. The species was first described from a series of isolated fossil seeds in chert . 49. The dank walls are shot through with green chert , a rock that Hiroaki covets. 50. Among petrologists, chalcedony is sometimes considered separately from chert due to its fibrous structure.
