[Illustration: Layer D (Between 5,800 and 6,600 years old)] [Illustration: Layer L (Between 5,800 and 6,600 years old)] [Illustration: Layer R (More than 8,750 years old)] [Illustration: Layer W (line pattern), and Layer Y (stipple pattern) (About 450 years old and 3,250 to 4,000 years old, respectively)] TABLE 1.—_Characteristics, sources, and ages of pumice layers, Mount Rainier National Park_ [Based on studies by D. R. Mullineaux] Common range of thickness in park Pumice West East Common Color Source Approximate layer side side range in age in 1968, (inches) (inches) diameter or limiting of pumice dates (years fragments ago) (inches) X Absent [1] ¼-2 Light olive Mount 100-150 gray Rainier. W 0-1 1-3 Medium White Mount St. [2]450 sand Helens. C Absent 1-8 ¼-8 Brown Mount 2,150-2,500 Rainier. Y 5-20 1-5 Coarse Yellow Mount St. 3,250-4,000 sand Helens. D Absent 0-6 ¼-6 Brown Mount 5,800-6,600 Rainier. L Absent 0-8 ¼-2 Brown Mount 5,800-6,600 Rainier. O 1-3 1-3 Flourlike Yellowish Mount About 6,600 to fine orange Mazama. sand R Absent 0-5 ⅛-1 Reddish Mount 8,750-11,000? brown Rainier. The next two eruptions of Mount Rainier occurred between 5,800 and 6,600 years ago. Again, pumice spread over the area east of the volcano. The older pumice, which we call layer L, covers a band only a few miles wide that extends to the southeast from the volcano (fig. 8). The younger pumice, layer D, covers an area at least 10 miles wide directly east of the volcano. The distribution of both deposits shows that there were strong directional winds during the eruptions. The long, narrow pattern of layer L probably was caused by strong northwesterly winds during a short-lived eruption. The pattern of layer D was caused by winds from the west.