LIN DORK N.I 



PAYETTE FORMATION. 633 



sandstones (as at Table Mountain near Boise; see PL LXXXVIII) 

 or clayey semiconsolidated sandstones. Heavy masses of conglomer- 

 ates and gravels begin to appear at Table Mountain, and reach their 

 greatest development opposite the mouth of Boise River, in the high 

 ridge extending in a westerly direction. Purely clayey deposits are 

 rarer, occurring only in convenient sheltered locations near the shore 

 line or in places where volcanic eruptions took place. The basal part 

 of the formation contains, at Horseshoe Bend, Jerusalem, and other 

 localities along the Payette, small coal seams. In the clay accom- 

 panying these coal seams vegetable remains are of frequent occur- 

 rence. The following forms were identified by Professor Knowlton: 



Two miles southeast of Marsh post-office, on the Payette, is a small 

 coal prospect. The disturbed beds of the Payette formation lie here 

 on a sharply sloping surface of granite. At this place the following 

 forms were found, together with many new species : 



Sequoia angustifolia ? Lx. 

 Quercus consimilis Newb. 

 Acer trilobatum productum ? Heer. 



One mile southeast of Marsh, along the road to Willow Creek, a few 

 hundred feet above the river, is an outcrop of yellowish-gray "chalk," 

 or diatomaceous earth, intercalated in the Payette beds and capped 

 by basalt. In this the following forms were found, in an excellent 

 state of preservation : 



Salix angusta Al. Br. 



Quercus consimilis Newb. 



Q. simplex Newby. 



Platanus aspira ? Newb. 



From Cartwright's ranch, on Shafer Creek, 4 miles southeast of 

 Horseshoe Bend post-office, the following forms were identified, together 

 with several new species. This is an excellent locality, and the leaves 

 embedded in a dark clay shale are beautifully preserved. 



Sequoia angustifolia Lx. 

 Salix angusta Al. Br. 

 Ficus ungeri Lx. 



This area is separated from the main one by a small ridge of gran- 

 ite, but that the two formations are identical admits of no doubt. 

 The beds are here disturbed, dipping west at 20 to 25. The plants 

 were obtained near the base of the series, of which about 800 feet of 

 alternating, fairly consolidated shale and sandstone are exposed. 

 The elevation is 3,500 feet. 



.Near Idaho City another detached mass of lake beds is preserved 

 at an elevation of from 4,000 to 4,500 feet, the occurrence of which is 

 described more in detail in Chapter III. From the middle of a series 

 800 feet thick the following plants were obtained: 



Sequoia angustifolia Lx. 



Ulmus speciosa Newberry. 



Betula angustifolia Newberry. 



