Recently another extensive fossil forest has been found on the divide between the Gallatin and Yellowstone Rivers in the Gallatin Range of mountains, in Park and Gallatin Counties, Mont. This forest, which lies just outside the boundary of the Yellowstone National Park, is said to cover 35,000 acres and to contain some wonderfully well preserved upright trunks, many of them very large, equaling or perhaps even surpassing in size some of those within the limits of the park. Two of the best preserved of these trunks are shown in figures 2 and 3, which are here reproduced by the kindness of Mr. E. C. Alderson, of Bozeman, Mont. In the beds of the streams and gulches coming down into the Lamar River from Specimen Ridge and the fossil forests one may observe numerous pieces of fossil wood, which may be traced for a long distance down the Lamar and Yellowstone Rivers. The farther these pieces of wood have been transported downstream, the more they have been worn and rounded, until ultimately they become smooth, rounded “pebbles” of the stream bed. The pieces of wood become more numerous and fresher in appearance upstream toward the bluffs, until at the foot of the cliffs in some places there are hundreds, perhaps thousands of tons that have but recently fallen from the walls above. One traversing the valley of the Lamar River may see at many places numerous upright fossil trunks in the faces of nearly vertical walls. These trunks are not all at a particular level but occur at irregular heights: in fact a section cut down through these 2,000 feet of beds would disclose a succession of fossil forests (see fig. 4). That is to say, after the first forest grew and was entombed, there was a time without volcanic outburst—a period long enough to permit a second forest to grow above the first. This in turn was covered by volcanic material and preserved, to be followed again by a period of quiet, and these more or less regular alternations of volcanism and forest growth continued throughout the time the beds were in process of formation. GEOLOGIC RELATIONS. While these fossil forests were growing and being entombed, much of the area now within the limits of the park, as well as large adjacent areas, was the scene of tremendous geologic activities. After the Cretaceous period (see diagram p. 28), there was a time of great volcanic activity, which appears to have lasted until perhaps the beginning of the glacial epoch. There were many active volcanoes just west, north, and west of the park, and some in the park itself. From these volcanoes vast quantities of material were poured out, building up in places whole mountain ranges. Thus the major portion of the great Absaroka Range, just east of the park, as it appears to-day, was built up of volcanic material. [Illustration: Fig. 4.—Ideal section through 2,000 feet of beds of Specimen Ridge, showing succession of buried forest. After Holmes.]