. Brigham Young University science bulletin. Biology -- Periodicals. 10 BmcnAM VoiNx; Univeksity Science Bulletin In all areas lu-ar Westwalcr wIhtc the plant- beariiii; asli lias hi-en exainiiu'd, tht" contact be- tween the ash and the nnclerl\ ing coal seam is very sharp and easily distinguished (Fig. 5). In addition, the lowemiost portion of the ash contains large nnmbers of root and rhizoid- like structures, often in such profusion as to form dense mats of these structures (Fig. 6). Leaves are scarce in the lower portion of the ash with the exception of poorly preserved, often broken
. Brigham Young University science bulletin. Biology -- Periodicals. 10 BmcnAM VoiNx; Univeksity Science Bulletin In all areas lu-ar Westwalcr wIhtc the plant- beariiii; asli lias hi-en exainiiu'd, tht" contact be- tween the ash and the nnclerl\ ing coal seam is very sharp and easily distinguished (Fig. 5). In addition, the lowemiost portion of the ash contains large nnmbers of root and rhizoid- like structures, often in such profusion as to form dense mats of these structures (Fig. 6). Leaves are scarce in the lower portion of the ash with the exception of poorly preserved, often broken specimens. One of the more im- portant identifiable fossils common in this region of approximately one inch in thickness is the rhizome of Equmtum lijeUi Mantel with at- tached tubers. Immediatelv above this rhizome region is a horizon containing numerous well-preserved leaf impressions. This region contains foliage belonging almost exclusivelv to the three fern genera Matotiklitiin, Astnilo])tcris, and Gleich- enia. This zone is approximately five to eight inches thick and is literally full of beautifully preserved specimens. At the upper portion of this dense foliage region, the color and composition of the ash changes somewhat (Fig. 5). The ash becomes noticeabh darker in color and somewhat silty- carbonaceous in composition. Many of the fos- sils found in this region differ taxonomically from those found lower in the ash. While the three genera Matonklitim, Astraloi)t('ri.'i and Gleichenia are still present as leaf impressions in this region, thev are not as dominant as they were in the lower portions of the ash. Plant fossils in this upper region represent several different genera. The greatest taxonomic diversity in the Westwater flora occurs within this zone. Significantly, Equisetuin rhizomes reoccur in this upper region after being noticc- ablv rare in collections from the middle portion of the ash. The contact between tlu' ash and the upper coal seam is not as sharp a
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