Tlic Surface Tctision of VVaJcr. — Ladd. 28 1 
face on irrigated lands where the water supply is insufficient 
to establish drainage beneath the surface. 
The same process which produces shrinkage and consolida- 
tion of clays, under certain conditions, results in the formation 
of clay stalactites. I have seen, pendent from overhanging 
banks of clay, stalactites which, though comparatively small, 
resemble exactly in form, the stalactites produced by the pre- 
cipitation of calcimn carbonate on the evaporation of drip- 
ping waters in caverns. The first of these seen were collected 
with the idea that they consisted of some s?.lt soluble in surface 
waters. Examination, however, showed them to be composed 
wholly of minute particles of quartz and scales of kaolinite. As 
opportunity offered the manner of their formation was investi- 
gated and found to be similar to that of our ordinarv stalac- 
tites, except that the whole process is physical. Water, per- 
colating through the clay mass above, carries with it some of 
the finer material, and where points of equilibrium are estab- 
lished between evaporation and supply these interesting forms 
result, the occurrence of which I have never seen recorded. 
Having once observed them, they have since come fre- 
quently under my notice. At Rich Hill, near Knoxville, Ga., 
where a variety of Eocene beds overlie cross-bedded sands and 
clays of the Lower Cretaceous, a section of two hundred feet 
is exposed in an immense gully. Here, besides small pendent 
stalactites, thin wavy ribbons of clay from two to three inches 
broad are attached, edge-wise, to the sandy walls. Some of 
them, three feet in length, resemble, in miniature, the "welt- 
beriihmten Vorhang" of the Adelsberg Grottoes. 
Of the same nature as these occurrences are the thin coat- 
ings of clay which wash down from overlying beds, and like a 
coat of paint often conceal the character of the beds below. 
Capillarity does not necessarily enter as a cause, but sur- 
face tension operates to contract and to consolidate the parti- 
cles suspended in the evaporating water. 
The main facts, in connection with the action of surface 
waters in a chemical way are too well known to need discus- 
sion here. 
Cjranting that the circulation of water in rock, soils and 
clays, takes place as outlined above, it follows that the pro- 
cesses which lead to the decompositions and alterations of the 
