. Bulletins of American paleontology. â â *-v .V*- *". Text-figures 21 and 22.âPhotographs taken in 1968 illustrating the method of digging clay at the Rockford Brick and Tile Company Quarry {Locality 35. Appendix). Figure 21 shows equipment used to dig clay and load it into trucks at claypit. The freshly dug face exposed 6 meters of the Juniper Hill Member below, and the basal meters of the Cerro Gordo Member above. Figure 22 shows a slightly weathered face of the lower Cerro Gordo with its basal silty unit (marked by the presence of the brachiopod GypiduUi) above the Juniper Hill. A
. Bulletins of American paleontology. â â *-v .V*- *". Text-figures 21 and 22.âPhotographs taken in 1968 illustrating the method of digging clay at the Rockford Brick and Tile Company Quarry {Locality 35. Appendix). Figure 21 shows equipment used to dig clay and load it into trucks at claypit. The freshly dug face exposed 6 meters of the Juniper Hill Member below, and the basal meters of the Cerro Gordo Member above. Figure 22 shows a slightly weathered face of the lower Cerro Gordo with its basal silty unit (marked by the presence of the brachiopod GypiduUi) above the Juniper Hill. Above the lower Cerro Gordo {Doinillina zone, with the Liodeina bed at the top), the upper part of the Cerro Gordo (so-called Spirifer zone) was stripped back to allow ease of quarrying. This is the most fossiliferous portion of the Cerro Gordo, and fossils could be collected in place in the background where each bed was exposed in sequence, or fossils could be collected from this unit in piles of stripped material. commonly established on the basis of type specimens only, and sometimes on external characters, or on growth characteristics known to vary greatly in living coral populations. At another level, genera are regarded as convenient names for groups of similar, apparently related, spe- cies. There is a tendency among some coral taxono- mists to utilize genera in the sense of "superspecies", where genera are expected to be easily identifiable on the basis of a few morphological characters. Where species are variable and boundaries between species are difficult to define, it is to be expected that genera consisting of these variable species will likewise be difficult to define on the basis of one or a few char- acters. In the systematic paleontology that follows, species are identified on the basis of populations where pos- sible. Where samples were small, but no affinity for it can be determined, the species is listed as "species A", signifying that
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