BOYS' OWN COLUMN.

Auckland Star, Volume LXII, Issue 192, 15 August 1931, Page 2 (Supplement)

BOYS' OWN COLUMN.

WAITOMO'S JEWELLED CAVERN. SPARKLING DIAMONDS SET IN RICH VELVET. Dear Boys,— Continuing from last -week's letter, which dealt with the Avranui cave of the Waitomo group, we shall proceed down the mile or so of road to the original Waitomo cave. But first it will be interesting to learn something about stalactites and stalagmites. A stalactite Is like an icicle, and is formed in something of the same way by water, which trickles down and hardens itself into a solid. In an icicle, however, it is cold which is hardening the water into solid ice, while in the water forming a stalactite the hardening matter is in the water itself, which contains some mineral substance dissolved in it- In kettles and water pipes this mineral is held in solution (as water holds dissolved sugar or salt) and the sides become coated with the mineral. In a stalactite the mineral gradually grows downwards from the place where the drops begin to fall. A stalagmite is merely a stalactite pointing upwards from the floor, usually of a cave, on to which the water is dripping, and is formed in much the same way, climbing upwards instead of downwards. Frequently these things meet, and when this happens they make a wondrous natural spectacle in the gloom of a cave. The mineral in this case is limestone, and it is interesting to note that, unlike an icicle, there is a hollow core through the centre of every stalactite, although, of course, the formation growing from the bottom of the cave is solid. Growth is very slow, as can be imagined, and it takes nearly 300 years to form one cubic inch of solid material. Undoubtedly the most beautiful sight in the Waitomo cave is the wonderful glowworm cavern—a huge dome over the surface of an underground river. Having been enjoined to keep strict silence, we boarded the large flat-bottomed boat and pushed off into the darkness. Oars were not used, for the boat was guided by means of a wire running round the side of the cave. Imagine the brightest and biggest stars of the sky bunched together, the heavens blackened and the stars trebly bright, and you have some conception of the right beauty of the glowworm cave. Picture miriads of flashing diamonds set in rich black velvet, and perhaps you have a truer representation of this gem of nature, which is reflected in the dark waters of the underground river. /"JS The glowworm of the cave is not j the glowworm of the bush, and next week I think the story of this interesting V*/ little creature would form a suitable " topic for my weekly chat.