FOSSIL FORESTS OF YELLOWSTONE PAEK. 



25 



ing thin sections under the microscope it is possible to distinguish 

 the different kinds with reasonable accuracy. As the result of such 

 study the following species have been detected : 



Magnificent redwood (Sequoia niasnifica ) . 

 Alderson's pine (Pityoxylon aldersoni). 

 Amethyst pine (Pityoxylon ametliystinnm ) . 

 Lanrel ( Lanrinoxylon pnlcbrnni ) . 

 Aromatic bay (Perseoxylon aromaticnm) . 

 Hayden's sycamore (Platanininm haydeni). 

 Knowlton's sycamore (Plantanininm knowltoni). 

 Felix's buckthorn (Rhamnacininm radiatnm). 

 Lamar oak (Qnercininm lamarense). 

 Knowlton's oak (Qnercininm knowltoni). 



Although only three kinds of coniferous trees have thus far been 

 found in the fossil forests of the park, fully 95 per cent of all the 

 trunks belong to these three species. The preponderance of coni- 

 fers is probably due to the facts that they were presumably more 

 abundant in the beginning, and that, in general, coniferous wood 

 decays less rapidly than that of most of deciduous-leaved trees. But 

 the conditions were so favorable for preserving any wood that it is 

 joerhaps strange that not more trunks of deciduous-leaved trees have 

 been found there. As it is, however, a greater number are known 

 from the park than from any other region. Thus, the Arizona fossil 

 forests embraced only two species of deciduous-leaved trees; the 

 Calistoga (California) wood only one species, and the forest at Cairo, 

 Egypt, only four species. 



The 10 species of trees represented in the fossil forests of the park 

 are by no means the only fossil plants that have been found. The fine- 

 grained ashes and volcanic mud in which the forests were entombed 

 contain also great numbers of impressions of plants, many of them 

 very perfectly preserved. Most of these are impressions of foliage, 

 such as fronds and leaves, but they include also roots, stems, branches, 

 fruiting organs, and even what is believed to be the petals of a large 

 magnolia flower. About 150 different kinds of fossil plants have 

 been found in the park, 80 in the same beds with the forests, and 

 most of the others in slightly higher and younger beds. The list 

 embraces 10 ferns, among them a fine chain fern (Woodwardia) , 

 several aspleniums, and a beautiful little climbing fern (Lygodium). 

 The horse-tails (Equisetum) are represented by 4 species. The 

 conifers include no less than 6 species of pines (Pinus), a yew (Tax- 

 odium), and 2 sequoias. These have been identified either from the 

 foliage or the cones, and it is more than likely that some of the 

 specimens may represent organs that belonged to trees represented 

 by the fossil trunks, but as they have never been found connected 

 they have been described separately. The monocotyledons, or plants 

 with parallel-veined leaves, are represented by only a few forms. 



