442 GEOLOGICAL EXCURSION TO THE ROCKY MOUNTAINS. 



Between the Laramie and the Denver beds is a narrow outcrop of 

 the Arapahoe formation, which is, however, exposed in very obscure 

 outcrops in this region. It occurs as a narrow band of steeply 

 upturned strata apparently conformable with the Laramie. 



In a wide aniygdaloidal zone in North Table mountain there' is a 

 succession of zeolites, which have been described in detail." 6 Tin; 

 occurrence is interesting for the distinct succession of species and for 

 tin 1 unusual development of certain forms. 



In the Dakota hogbacks north and south of Golden are also lire clay 

 beds. These are used in manufacturing a very tine quality of tire 

 brick, furnace muffles, crucibles, etc. There is also a large manufac- 

 tory of ornamental brick in Golden, the material used being largely 

 the plastic clays of the Laramie. The Colorado State School of Mines 

 is located at Golden. It has a fair museum, and is rapidly growing. 



In Clear Creek canyon, above (iolden, are found exposures of the 

 Archean gneisses and schists. At about (> miles (10 km.) north of 

 (iolden, Ralston creek issues from the mountains, cutting across the 

 sedimentary beds and affording another excellent section which very 

 nearly resembles that at Morrison. Fig. 27, p. Ill (after Holmes,) rep- 

 resents the section displayed on the north bank of Van Bibber creek, 

 a small stream north of North Table mountain. This illustrates the 

 section exposed in better detail along the line of Kalston creek, which 

 crosses the held of view along the middle-ground. There is here a 

 great development of the Triassic red beds, the Jura, and the Dakota. 

 There are extensive quarries of the lower sandstones. On the right 

 hand of tin; figure are seen a number of conical hills of basalt, repre 

 senting necks or dikes, through which the lavas of Table mountain 

 ascended. The terrace formations of the plains are very (dearly repre- 

 sented. 



