Genesis of Iwn- Ores. — Kim ball . 373 
replacement precludes any such intermittent action on the part of 
a single agency. 
XIII. Replacement of Trrtuiry Limestone. Hesse. 
Epigenesis of oolitic iron-ores in Tertiary limestone of Rhenish 
Hesse has substantially been described b}' Tecklenburg as re- 
placement of an oolitic limestone, the source of infiltrations of 
iron salts being an upper ferriferous limestone of the same 
series. * 
A/F". Rephiceinent of Pre-piihnozoic crystalline li)nestone.i, JJaiiat. 
Some striking Examples of replacement of crystalline limestone 
at Russklierg (Bauat) by siderite passing into hematite on the one 
hand, and into magnetite on the other, were in other terms de- 
scribed by Mr. Rafael Hofmann, in the year 1854. t 
Like the other more important iron-ore developments of the 
Carpathians, these are upon horizons of pre-palteozoic lime- 
stones. 1 
Among other well-known developments of siderite and its de- 
rivatives in continental Europe within limestone strata, suffice it 
in passing to mention those of Carinthia and Carniola; and not- 
abh' those of the Styriau Erzberg near Eiseuerz in Austria; also 
tliose of the Rhenish province of Coblentz and Siegen in Grer- 
anany. ^ 
Commonly regarded as epigene products, these have usually 
been described b}' German authorities in various terms as St()cke, || 
Lagerst5cke, Gangstocke, and FliUze, sometimes of direct deposi- 
tion successive in relation to enclosing strata, sometimes as me- 
chanical fillings or -in-washes' of pre-existing spaces; and, again, 
as chemical segregations. In most of the conspicuous instances 
named, circumstances of environment and topography are such 
as to indicate more or less clearly molecular replacement of lime- 
stone or dolomite. 
M. Sibertz}', of the Geological Survey of Russia, considers cer- 
*Zeitsch, Berg — Hlitten — and Salinen Wesen xxi.x; 1881, 210. 
tGangstudien, II, 4G8. 
JVon Hauer— Geol. Oest. -Ungar. Monarchie, 1875, 194. 
ijSenft. Geogaosie 1876, 451; Von Hauer loc. cit. 22;J. 
I Dr. E. Rej^er truthfully says that Geology and the miner call that 
form, as to whose form nothing is known, a Stock. (Berg-u-Huetten- 
mannische Jahrbuch xxix, 1881, 26.) 
