570 Transactions.— Geology. 
much like the two formations of the same name already described, but 
there are certain differences in its characters by which it may generally be 
recognized in the field; and these are, first, the perpendicularity with which 
it stands up in cliffs, its greater homogeneity, and a peculiar form that the 
fracture of the rock takes as it weathers and falls, which is conchoidal, like 
the fracture of flint, only on an immensely larger scale. It seems also more 
liable to small slips. Standing on the Purohutangihia range, and looking 
northwards towards the Wairoa, these beds may be distinguished from the 
Middle Papa (on which they rest, beyond the limits of the brown sandstone) 
by the enormous number of land-slips which dot the surface of the country, 
giving it an appearance of great barrenness : this is far from being the case, 
however, for whenever the soil is derived from the Papa rock, it is very 
rich indeed. 
The quantity of material which is yearly precipitated into the beds of 
the streams off the surface of these Papa hills in this district is something 
incredible, and will ever be a constant source of heavy expense in keeping 
the roads open. During the heavy and continued rain of last January, 
many of the roads were simply impassable by horses for weeks, and many 
millions of tons of clay must have fallen. Some of the slips were of large 
extent. I saw one myself which was three-quarters of a mile long and a 
a quarter of a mile wide, which had slid down the side of a mountain into a 
gully, carrying everything before it. Large trees were uprooted and left, 
many of them with their heads buried deep in the ground and their roots 
high in the air; and large Rimu trees, six feet in diameter, were broken 
short off in a manner that would scarcely be believed, whilst enormous 
masses of rock as large as cottages were piled up pell-mell on the tops of 
the trees. Another slip is described by one of the Surveyors as over a mile 
long, which fell into the Waiau River, damming up its course and causing a 
long narrow lake to form, three miles long. 
I have already spoken of the fertility of the Papa soil. This is proved 
by the readiness with which the grass takes on the surface of the newly- 
formed slips. 
Brown Papa and Calcareous Sands. 
Above this Upper Papa another bed of conglomerate is seen in the Esk 
Valley, but it is of no great extent; and above that again are a series of cal- 
careous clays, which have a very small surface exposed horizontally, owing 
to the ease with which they disintegrate and are carried away by water. 
They are generally fossiliferous, and range upwards for about 500 feet, and 
are then overlaid by a hard calcareous sandstone, also containing numerous 
fossils, the most common ones being species of Arachnoids and Placuna- 
nomia, It is this sandstone which forms the lowest strata seen at Scinde 
