676 



SCIENCE. 



[N. S. Vol. I. No. 25. 



the surface of contact of sphere and fluid 

 being conducting, currents will be incited 

 in the fluid that will pass into the sphere 

 and out again. 



In the case of the earth there is no fluid 

 with reference to which the solid earth per- 

 forms a total differential rotation ; still 

 there are partial diifereutial rotations due 

 to moving streams, ocean currents, tidal 

 waves and air currents. Such a field, if it 

 exist, can be differentiated with the aid of 

 the potential theorj'. 



Purely local disturbances would consti- 

 tute a fourth — the ' anomalous field.' 



We as yet have no satisfactory answer as 

 to the origin of the earth's prrmarjr mag- 

 netic field, neither has the astronomer an 

 answer to the querj' ' Whence the moon.' 

 He, however, accepts the moon's existence 

 and computes its disturbing effects upon 

 the earth's motions. Just so it is with the 

 earth's magnetism. We do not know 

 whence it has come, but we know it is 

 there. We know that to-day the mag- 

 netic earth is rotating about an eccentric 

 axis, and so let us ask ourselves What 

 is the effect of the self-inductive action of the 

 rotating magnetic earth f Sow is the prin- 

 ciple of the conservation of energy when applied 

 to the motions of the magnetic earth to he ful- 

 filled f L. A. Baueb. 



ON A DEVONIAN LIMESTONE-BBECCIA IN 

 SOUTHWESTEEN 3IISS0VEL 

 The brecciated limestone which it is pro- 

 posed to describe in this paper outcrops 

 near the base of Eagle Eidge, on the west 

 side of the valley of Drj- Creek, five miles 

 west of the town of Galena, county seat of 

 ■Stone County, Missouri. The several mem- 

 bers of the Devonian strata in this portion 

 of the State are, in their normal condition, 

 verj' regular and evenlj' bedded, and are 

 perfectly conformable, from their base, to 

 and with the overlying Kinderhook Group. 

 They rest, with slight local unconformity. 



on the magnesian limestones of the Ozark 

 Series, and then out toward the east, at the 

 expense of the lower members, each stratum 

 overlapping that which is under it. In the 

 vicinity of the limestone breccia they pre- 

 sent the following sections : 1. Green Shale, 

 7 feet. 2. Shaley Limestone, 10 feet. 3. 

 Speckled Crinoidal Limestone, 3 feet. 4. 

 Basal Conglomeratic Sandstone, 4 inches. 



Proceeding south along the west side of 

 the vallej^ we find the first indication of 

 a disturbance in the form of a gentle undu- 

 lation of the upper portion of the shaley 

 limestone. No. 2 of the section. A few 

 hundred yards further we encounter the 

 first of a series of huge masses of breccia, 

 consisting of the light gray, amorphous 

 limestone and thin shale of No. 2, broken 

 into angular fragments of various sizes, and 

 recemented, pai'tty by a similar substance, 

 and partly by the subsequent infiltration of 

 calcareous matter occurring now in the form 

 of calcite. The original bedding planes 

 have been mostly obliterated, and the brec- 

 cia weathers out along the hillside in boul- 

 der-like masses, 10 to 20 feet thick, and 50 

 to 100 feet in width. A stratum of shaley 

 limestone at the base of these masses parti- 

 ally retains its original appearance, and 

 from its relation to the more massive brec- 

 cia overlj-ing it the whole is seen to have 

 been subjected to violent contortion and 

 fracture, such that boulders of hard lime- 

 stone have been forced into the midst of 

 calcareous shale. There are about half a 

 dozen of these masses exposed along the val- 

 ley side, in a distance of about 1000 feet ; 

 then the undulations decrease, and at one- 

 half mile from where the first disturbance 

 in the strata was noticed thej' entirely 

 cease, and from thence down the valley the 

 strata are in their normal condition. 



There is no indication of the action of 

 water in the formation of the breccia. All 

 the fragments are sharplj' angular, and fre- 

 quentlj" a fossil has been broken through 



