New Hebrides, of 1913-14,. 533 



surrounding area. This explosion on Ambrym formed a volcanic 

 trough more than a mile long by about a quarter of a mile wide, with 

 its floor in places 50 feet below sea-level ; as it is breached to the 

 north, the sea has poured in and the site of the hospital is now 

 occupied by a somewhat fiord-like inlet, which is T-shaped, and has 

 a threshold across its entrance. Subsequently a submarine eruption 

 built up the base of Sealark Hill, which has been raised to the height 

 of 330 feet, and has extended the island for about half a mile 

 seaward. 



The change produced in the outline of this part of the island by the 

 eruption is shown on the map, PI. XXXIII ; the broken line represents 

 the original course of the coast, taken from the Admiralty Chart of 

 1894, and the full line represents the coast after the eruption of 1913 

 from the survey of H.M.S. Sealark under Commander Hancock. 



(b) The Lava Pipes. 



A second remarkable feature of these Ambrym eruptions is that 

 the lava-flows are extraordinarily narrow in proportion to their 

 length. Thus in the eruption of 1894 the lava stream which 

 entered the sea near Krong Point was over 6 miles long. Admiral 

 Purey-Cust (1896, pp. 7, 13, 16) records its width at four places — 

 at the shore, where it was 20—30 yards wide ; further inland, 

 30 yards wide ; at its sharp bend east of Fo-luk, 30 yards wide ; 

 and at its upper part along its east to west course, where it was in 

 places only about 10 yards wide (Purey-Cust, 1896, No. 1, p. 16; 

 but said to be 10 feet wide in 1896, No. 2, p. 600). The lava sheet 

 west of Fo-luk fed two streams which flowed south-westward ; both 

 are represented on the map as very narrow. The southern stream 

 discharged from a tongue some 300 or 400 yards wide (Purey-Cust, 

 1896, p. 9) projecting from the wide lava sheet. The lava stream 

 of 1913 which reached the sea at Baulap, flowed from the eastern 

 end of the Fo-luk fissure ; it was 5 miles long and is represented on 

 the Admiralty Chart as a long narrow sinuous line. The discharge 

 from the vent to the south-east of Mt. Marum formed a wide lava 

 sheet, 3 miles in length from east to west, and nearly 2J miles wide 

 from north to south ; at its western end it gave rise to a lava stream 

 which was discharged in January, 1914, and reached the sea at Port 

 Vato ; its length was 5 miles, and it also is represented on the new 

 edition of the Admiralty Chart as a long narrow stream. 



The Admiralty Chart no doubt indicates only the approximate 

 course of the lava streams, and it is not intended to give precise 

 evidence as to their width. Exact information as to the width of the 

 flows would be of value. The available evidence indicates that they 

 are remarkably narrow. Admiral Purey-Cust remarks (1896, p. 13) 

 that the stream west of Fo-luk flowed down a deep gully ; and the 

 narrowness of the streams is doubtless due to their being confined 

 between the banks of steep gullies. A stream 6 miles long and 

 maintaining an average width of 30 yards must be fed by the flow of 

 material down the centre while the outside has cooled to form a solid 

 pipe. 



