1845.] Account of certain Agate Splinters, 757 



the section of which is yearly exposed as the surface crumbles. The 

 kunkur in this bed is scattered through the thickness of the soil, with 

 little visible stratification ; existing there in small drops of the size of 

 pocket-pistol bullets, which being found collected in the rocky beds of 

 torrents, are used as gravel for garden walks. 



4. As the cliffs of clay aforesaid crumble away, fragments of agate, 

 milk-white, pellucid or streaked, are brought to light, sown equally 

 through their substance ; not as complete pebbles occasionally fractur- 

 ed or chipped, but universally as fragments, such as might be shiver- 

 ed from pebbles placed between an anvil and a sledge-hammer ; 

 about half of the specimens which I happen to have preserved, accom- 

 pany this letter. They are faithful samples of the general appearance 

 of this mineral in the clay stratum. It will be observed that the sur- 

 face is always un corroded, so that they must have been shivered in 

 their present position as parts of a clay-bed twenty feet in depth ; 

 or more probably, immediately previous to their present location : for, 

 all agates acquire a milky crust by long exposure to the action of the 

 elements. They are found in abundance at the foot of all the clay 

 cliffs, and may be picked out of the strata on ascending. I have 

 seldom if ever found a complete series of fragments constituting a 

 pebble : whence I would argue, that they were shattered previous to 

 being involved in the clay. They are the only stones,* occurring in 

 this bed, and I have never found one of them unshattered, although 

 there are abundance such in the river bed close by, and the trap rock 

 is full of perfect agate pebbles. 



5. You will observe how violent and decided must have been the 

 concussion, to shiver so hard a stone into splinters so sharp and slen- 

 der ; an application of force, known in Nature at present only at 

 the foot of water-falls having a shallow basin, or upon any rocky 

 ledge at the base of a volcano. Were the fragments found in such a 

 position, the projection upon their original masses of other rocks, might 

 have sufficed to strike them off; but the clay matrix in which they 

 are involved, would have preserved agates unshattered beneath the fall 

 of mountains. 



* The river channel contains agates, rolled masses of jasper, porphyry, sandstone 

 and limestone. The soil around has few stones excepting boulders of trap and no- 

 dules of white quartz. 



