4 PROCEEDINGS OF THE NATIONAL MUSEUM vol.73 



No intrusive rocks younger than the Columbia River basalt were 

 noted in the region. In the Blue Mountains the only late Tertiary 

 intrusive rocks noted ^ were dikes of olivine basalt. 



Hot springs. — So far as the writer could learn in the region, the 

 only hot springs known on the upper parts of the John Day River 

 are at Ritter and that which lies in sec. 15, T. 13 S., R. 30 E., 3 miles 

 northeast of Mount Vernon and 32 miles due south of Ritter. Only 

 the first was visited. The present outlet of the Ritter spring lies on 

 the fault referred to, 32 feet above the river and 100 feet north of it. 

 Doubtless in an earlier period the outlet was higher but has been 

 progressively lowered as the river has carved its channel. The flow 

 was estimated at 35 gallons a minute and the temperature at the 

 outlet is 110° F. A few bubbles of gas rise from the outlet and the 

 odor of hydrogen sulphide is noticeable near by. The taste of the 

 water is mildly alkaline. No analysis is available but where it flows 

 over rocks it deposits a thin film of calcium carbonate and a little 

 sulphur. 



The zeolites described in the second part of this paper occur in 

 two ways, (1) on the line of fault referred to and (2) in the vesic- 

 ular and scoriaceous phase of the lower flow. Only traces of zeolites 

 were noted in the two OA'erlying flows. 



The fissure is separable into three parts. The southwest part ih 

 filled with stilbite, 4 to 6 inches wide, which is separated from the 

 central part by 7 feet of unaltered basalt. The central part shows, 

 in succession beginning at the southwest wall, a layer of stilbite as 

 much as three-fourths of an inch thick (pi. 2&), which locally en- 

 velops angular fragments of calcite; a layer of scalenohedrons of 

 clear pale yellow calcite, 4 to 6 inches thick; a layer of arborescent 

 calcite 1 to 3 feet thick; a layer of clear yellow calcite, and, finally, 

 on the northeast wall a layer of stilbite, 2 to 6 inches thick. Here 

 the order of deposition appears to be calcite, stilbite, calcite. 



In the scoria over the lowest flow, at locality 12, analcite is most 

 abundant in area 10 feet in diameter. Here good crystals rest on 

 a layer of mesolite. (PI. 2a.) At locality 9 some vesicles in the 

 scoria show scalenohedrons of calcite overlain by rhombs of chaba- 

 zite, which in turn are overlain by fibers of mesolite, and others are 

 completely filled with fibrous mesolite. At locality 8 fragments of 

 scoria are covered with a layer of thomsonite one-fourth inch thick. 

 (PI. Ic.) This mineral is abundant here but was not noted else- 

 where. Near by, veinlets in the flow show (1) a layer of mesolite, 

 (2) rhombs of calcite, (3) milky opal which fills the remaining 

 voids. Opal was not observed elsewhere. South of the fissure, at 

 locality 6, in the upper part of the vesicular zone of the lowest flow, 



'Pardee, J. T., and Hewett, D. F., Geology and mineral resources of the Sumpter quad- 

 rangle : Oregon Bur. of Mines and Geology, vol. 1, p. 45, 1914. 



