58 REPORT — 1844. 



Van Diemen's Land. Norfolk and Philip Islands, the largest of the group, are about six 

 miles distant from each other, and about a dozen others, the Nepean and Bird Islands, 

 are little more than dry rocks distributed among them. Norfolk Island is not quite 

 5 miles long with a medium breadth of about 2f miles, and its superficies is said to be 

 8960 acres ; its greatest elevation is the double summit of Mount Pitt, 1050 feet high ; 

 its sea front is high and precipitous, presenting cliffs of 200 and 250 feet in height, 

 and the small streams which occupy the ravines in winter fall in cascades 30 or 50 feet 

 high into the sea. Philip Island is about 1^ mile long, with an average breadth off; 

 its most elevated point is probably 200 or 300 feet less than that of Norfolk Island. 

 It is everywhere precipitous, furrowed by deep channels and densely wooded, though 

 the timber is small and of little value. Both tliese islands are masses of porphyry 

 much decomposed on the surface ; and boulders of compact greenstone are abundant 

 in both, especially in the fields and water-courses of Norfolk Island, where they are 

 employed as building materials ; they are also found imbedded in the porphjTy at the 

 greatest depths to which the rock has been penetrated by wells or exposed in ravines. 

 Near the south-east extremity of Norfolk Island are extensive beds of sand and lime- 

 stone restino' on the porphyry; the limestone, which is the lowest formation, is from 

 12 to 20 feet thick, and occupies about 20 acres of comparatively flat land ; in two 

 places it has been fractured and upheaved from an angle of 10° to an absolute verti- 

 cality. It is thin-bedded, the laminae being usually 1 to 3 inches thick, of fine quality, 

 slightly mixed with sand, but yielding 90 per cent, of lime ; the sandstone appears to 

 be entirely a modern formation, lying upon and against the dislocated limestone ; the 

 bar and projecting rocks along the whole of the south-east front are composed of it, 

 but it is nowhere above 6 feet thick ; below it is found an unctuous black clay fuU of 

 vegetable remains, especially the leaves and seeds of pines and other island trees. 

 The sandstone is only compact on the coasts where it is still forming ; it contains marine 

 shells and incrusts the boulders of greenstone on the coast. Being porous and filled 

 with saline particles, it forms a bad building stone, the houses built of it requiring to be 

 rough c£ist with lime. Opposite the settlement which is placed on these beds, and 

 about 600 yards from the beach, Nepean Island rises to the height of 50 feet ; it is 

 about a quarter of a mile long, and of a horse-shoe shape open to the east. The limestone 

 of which this island is composed is used for the shafts of chimneys, its east and south- 

 east beach is formed of sandstone. No water has been found in it, and its vegetation 

 has within the last few years almost disappeared, owing to a colony of rabbits, which 

 having destroyed everything edible, have now themselves perished. It is reported 

 that in 1793 this island was only a boat's length from Norfolk Island, but that in 1797 

 two severe earthquake shocks were experienced, by the second of which the nearer point 

 of Nepean was submerged, and the channel altered to its present form. The rocks which 

 pave the channel between these two islands are almost all limestones, whilst elsewhere 

 they are porphyritic. The Bird Islands are rocks of porphyry distributed along the 

 north shore of Norfolk Island ; they are of no ceconomic value, and are tenanted only by 

 sea birds. 



On the Communication between the Atlantic and Pacific Oceans, tlirough the 



Isthmus of Tehuantepec. By Signer Gaetano Moro. Communicated by 



Mr. MuRCHisoN, P.R.Geogr.S. 



It is considered by Signor Moro, who has carefully surveyed the district, that the 

 communication between the Atlantic and Pacific Oceans might be accomplished 

 in several ways, by taking advantage of the rivers on the Isthmus of Tehuantepec, 

 which flow on one side into the Pacific, and on the other into the Gulf of Mexico, 

 and in a manner far more advantageous than by either of the proposed routes by Ni- 

 caragua or Panama. This new line is considerably to the north of the others, and the 

 country is said to be rich in the most valuable kinds of wood. 



This work being published, can be consulted by all geographers. 



On the Fish River of the North Polar Sea. By Richard King, ALD. 



The author stated that the source of the Fish River was discovered by Heam, 

 during his memorable journey to the Polar Sea, and that Captain Sir John Franklin, 

 having learnt from an Indian named Blackmeat that the outlet of this river was in 



I 



