PEBBLE CREEK. 211 



and belong to the Madison formation. On the north bank of Lamar River, 

 near the mouth of Soda Butte Creek, there is an exposure of 50 feet of 

 limestone. The beds are horizontal, from 2 to 4 feet thick, and possess a 

 peculiarly rough, weathered surface, but so far as observed do not cany 

 fossils and are not cherty. Another exposure nearer Soda Butte Creek is 

 found 200 feet above the river, the most prominent ledge being a fissile 

 limestone 20 feet thick, carrying variegated chert and Carboniferous fossils. 

 These beds dip west of south at 10°. These limestones form the low flat- 

 topped knolls which are so distinct a topographic feature of the southeast 

 base of Druid Peak, as they are quite unlike the topography prevailing in 

 the breccia areas. On the shores of the small lakelet which a landslide of 

 breccia has formed on the lower slopes of the peak the beds are tilted, 

 dipping west at 55° and striking north and south, but it is probable that 

 they have been dislocated by a landslide. 



PEBBLE CREEK. 



Light-gray, massively bedded limestones are exposed at the mouth of 

 Pebble Creek, forming a rounded knoll on the south side of the stream. 

 The rocks contain rather scanty fossil remains, which prove that the beds 

 belong to the Madison formation. These beds also outcrop along the north 

 base of Abiathar Peak, 1,300 feet above the creek bottom. Pebble Creek 

 has cut a narrow gorge through the limestone, whose beds form vertical 

 walls 100 feet high. The strata are nearly horizontal and are exposed for 

 300 feet above the channel of Soda Butte Creek. Above the mouth of the 

 stream the valley of Pebble Creek shows heavily wooded slopes, with no 

 exposures until, near its head, limestone again appears, being exposed on 

 both sides of the valley beneath a capping of andesitic breccias, as shown 

 in the accompanying plate (PI. XXVI). Above the creek on the spur just 

 outside of the Park boundary occurs a thickness of 800 feet of limestones, the 

 beds dipping at a low angle to the southwest. The west base of Baronet 

 Peak and the ridge of which it is the highest point show limestones dipping 

 from 1° to 5° S. On the south side of Pebble Creek, just north of the 

 limits of the area mapped, but within the Park, about 100 feet lower than the 

 low saddle that indents the ridge, occurs a mottled Cambrian limestone 

 carrying fragments of trilobites, the rocks being nearly horizontal. 



