The Nature Column.

Digger (Invercargill RSA), Issue 6, 23 April 1920, Page 4

The Nature Column.

BY "STUDENT."

"Student" would he glad to hear of any place in the Hokonuis where fossils ar * common. Whie on the subject 1 would like to point out that good fossil specimens are aiways acceptable to the local museum.

If a naturalist wants to spend a pleasant and profitable day without travelling any great distance, he or she, could not do better than take the train for Greenhills and proceed from there to the back beach. This beach is little known, but as a picnicing ground is superior to my mind, to either Bluff or Ocean Beach. Several streams of first class water cross the shore and firewood is in abundance. A nice piece of bush, steep sandhills — down which one may toboggan.if not too old — and a fair-sized lagoon shallow enough for kiddies to play in, makes up a list of attractions hard to beat. To the naturalist the place is particularly attractive. The marino iife is very abundant much more so than at the other places mentioned. This is perhaps accounted for by the fact, that a rocky headland jutg far ont to sea and protects the bay. In the sandhills one may find moa bones, and pieces of moa eggshell are everywhere. On the seashore are some large Maori middens in which the industrious seeker will nearly always find something worth carrying away. Considerabje numbers of axes, hammers, etc., have been found here, and the stone chips used by the Maoris as knives are always to be picked up. The Maoris sometimeg had a quarry for the stone used in making implements. It will be found that axes are mostly made from tough hard stone. I think the stone used at Backbeaeh was taken from some of the numerous basic dykes which are one of the most interesting features about the beach. The geologist will find be is on the aureole of rocks which surround the plutonic mass of the Bluff Hill. The dykes of igneous rock show that the older rocks have been cracked by the upheaval of the rock at the Bluff, and through the cracks the molten rock has welled up. That there has been more than one upheaval is evidenced by the fact that angular blocks from some dykes are included in other outcrops of a different cbemical composition, and which outcrops are necessarily younger. The basic dykes — tfcose having less silica in their composition — apparently break up readily, as below the hightide mark will be found square channels running across the rocks which were formerly occupied by basic rock. Aujgite crystals are fairly common. At the Bluff end of the beach is a large yem, of^ pegmatite, this heing white is easily disTin-guished from the surrounding rcck. Pegmatite is a rock in which the crystals are extra large. The botanist will find much to give interest. The native sandbinding sedge and the marram grass are growing stronglv, bit even so the sand is now running over the top of the hill toward the railway. The Rata with its venerable looking, gnarled branches, gives-a bright toueh of colour to the scene, when in bloom. The bush is mixed, and the walk through it on a good, track is very enjoyable. The pools on the beach are full of life, aai many named specimens collected therefrom are in our museum. The paua or pawa or mutton fish is some times abundant, and the irridesoent shells gleaming on the middens tell of many an ancient tribal feast. These middens by the way usually occur at a lower level than the place where the feasting took place. The nativeg after a meal getting rid of the debris by the simple process of throwii g it down the hill. The paua is not always plentiful on ihe rocks, for it seems to migrate. Whether this is due to seasonal changes in the tcmperature of the water, or whether it is owing to the search for food I am unable to say. If any of our seaside naturalists can help us out with an explanaticm it would be welcome. Seaweeds and those curious weedlike animals, such as t'.-e sea lillies, a,re in quantities. Here is a fine study for someone to take up. The seaweeds have never been fully dealt with, and there are large numbers to be fcund and named yet. A reef runs o-ut on the Bluff end of the beach forming a breakwater. Large starfishes, up to 24 irithes across are found here, and at certam times hosts of sea urchins. A local resident informed me that he had seen the rocks at -this point simply alive with sea urchins, or sea eggs as some people call them.

Space at present does not permit me to give a list of all the inteTesting things which may be se&n on th© seaward side of Greenhills, but I may deal with the mattor when the holidays come round a,gaiu.-»