50 REPORT—1845. 
On the Denudation of South Wales and the adjacent Counties. 
By A. C. Ramsay, F.G.S. 
* 
On the Geology of New Zealand. By Dr. Dizrrensacn. 
New Zealand forms a group of mountainous islands nearly as large as England and 
Wales, and its geological structure is rendered difficult of discovery by the primitive 
forests that fringe the coast, or, where these have been destroyed, by impenetrable 
thickets of the esculent fern. The fundamental rock is everywhere clay-slate, fre- 
quently containing greenstone dykes, as at Port Nicholson, Queen Charlotte’s Sound 
and Cloudy Bay; in the neighbourhood of the dykes the clay-slate sometimes assumes 
the character of a roofing-slate. On the banks of the rivers Eritonga and Waibo are 
terraces, or horizontal plateaux, fifty feet high, formed of boulders of the oldest trap- 
rocks, and similar terraces are seen on the sea coast round Cape Palliser, fifty or sixty 
feet above the sea. Anthracite cdal crops out in the small harbour of Wangarrie on the 
west coast of Middle Island, and there is a thin seam of anthracite in the hard gray 
sandstone on the east coast of the Northern Island. Limestone is described as oc- 
curring in the harbours of Kauria and Waingaroa on the west coast of the Northern 
Island ; it is crystalline, and contains fossils of the genera Pecten, Ostrea, Terebratula 
and Spatangus. Limestone is also found on the river Kaipara in the Bay of Islands, and 
copper pyrites has been obtained from the great Barrier Island, where it forms veins 
in the clay-slate. The coasts are in many places fringed with recent horizontal sedi- 
mentary deposits, consisting of loam, with fragments of wood and tree-ferns, blades 
of the Typha, &c.; and on the Northern Island the coast is often formed of volcanic 
conglomerate, containing magnetic iron sand near Cape Egmont, and Turritelle and 
oyster shells at the harbour of Parenga; near Tauranga, it is composed of decom- 
posing tufa, containing lignite and shells of Pectunculus, Natica, Pyrula and Ancil- 
laria. The small rocky islands of trachyte, lying off the coast of Northern Island, 
also bear marks of wave-action to the height of 100 feet above the present sea level. 
On the western coast of this island formations of sand are now accumulating, driven 
over the forests by the prevalent westerly gales. The interior of the Northern Island 
affords but a scanty vegetation, and the surface is everywhere covered with ordinary 
volcanic productions, derived from the lofty central group of mountains, some of 
which are extinct, others still active voleanoes; the lava appears to have been prin- 
cipally erupted from the base of the craters. The highest of these craters are Ton- 
gariro, 6000 feet in elevation, according to Mr. Bidwell, and Mount Egmont about 
9000 feet, by Dr. Dieffenbach’s thermometrical observations. There are also many 
lakes which appear to occupy ancient craters. The mountain chains of the Middle 
island are supposed to consist of primary rocks; quartzose sandstone and gray- 
wacke are met with at the height of 3000 feet; the lofty pyramidal summits are co- 
vered with snow, and deep narrow valleys separate the various ridges, and radiate 
from the central cones. Dr. Dieffenbach enumerates many localities at which he 
observed mineral springs, particularly between the Bay of Islands and Hokianga, 
where their temperature varied from 124° to 154°, and having an alkaline taste ; 
the surface was covered with sublimations of sulphur. Along the delta of the Waikato, 
hot springs rise from the escarpments of the hills, forming deposits like those of 
Iceland and St. Michael, Azores, containing 75 per cent. of silica. There is also a 
cold silicifying spring near Cape Maria. 
Dr. Dieffenbach has examined into all the traditions respecting the existence of 
the Moa, or great bird of New Zealand, and concludes that it has never been seen 
alive by any natives of New Zealand ; the rivers in which its bones have been found 
flow between banks from thirty to sixty feet high, and-as they are continually chan- 
ging their course the remains of the Moa may have been derived from tertiary fluvia- 
tile strata. 
On the Lake Parima, the El Dorado of Sir Walter Raleigh, and the M4 
Geography of Guiana, By Sir R. Scuompurex. : 
The author commenced by alluding to the ill-fated expeditions at the close of the — 
16th and commencement of the 17th centuries, in search of the El Dorade and its — 
