Page:Field Notes of Junius Henderson, Notebook 4.pdf/98

 mately horizontal zones.

The surface of the cliff itself has the appearance of being a thin, hard coat backed soft material, so that where a hole breaks through the surface weathering by action of wind proceeds more rapidly within and forms a cavity whose interior diameter is greater than that of the entrance. It is not unlikely that the hardening was accomplished by water descending along former cleavage planes and is now going on along invisible cleavage planes back of the present face of the cliff. These hard surfaces are irregular and largely responsible for the irregular appearance of the face of the cliff. There are many places where crevices etc. show the deposition of thin films of material. One tunnel - nearly vertical ? is seen on a vertical cliff, worn by water. It may disappear before many years by the breaking down of the face of the cliff. In the tufa there are many fragments of hard, much darker rock of various kinds. No rain tonight, partly cloudy all day, clear tonight. Set 9 mouse traps and 4 steel traps at dusk.