Art. XLIX.—A few Notes on Thermal Springs at Lyttelton.
[Read before the Philosophical Institute of Canterbury, 4th October, 1883.]
Hot springs are found on the sides of most active volcanos, and very often in the vicinity of extinct ones, hence their presence at Lyttelton is not to be wondered at; nor is it strange that the ones to be described should hitherto have been overlooked, for they are out of the way of ordinary travellers. On going along the road from Lyttelton to Governor's Bay, several beaches of sand and one of shingle are passed on the left. It is on the southern extremity of the last mentioned beach that the springs in question are situated, at a distance of about two and a half miles from Lyttelton, and half a mile from Raupaki (the Maori pa).
They are two in number; the more northerly one lies on a grass bank several yards above high-water mark. The water bubbles up from a muddy bottom into a brick well, about three feet in diameter, and two feet six inches deep. Thence it flows into a second and much larger cistern, which is used as a drinking trough for cattle. These troughs were, I believe, built by Mr. W. Webb, of Lyttelton, who, however, does not seem to have noticed the temperature of the water in them. The second spring, which is just within high-water mark, is situated about twenty-five yards to the south of the other, at the foot of a steep bank. The water flows out from a crevice in the rock on to the shingle, and runs down in a streamlet to the sea. Midway between the two springs the sand and shingle are cemented together by carbonate of lime into a crust several inches in thickness, that extends from high to low water-mark. In this cement numerous shells are embedded, apparently the same as those existing on the beach at the present day. Since the sea is continually washing over this incrustation, and breaking off pieces here and there, it is probable that at the time of deposition the outlets of the springs were further from high-water mark than they are now. At that time, too, the flow was probably greater, for in many other places between the springs there are patches of carbonate of lime coating the rocks, and in a crevice close by there are a number of small stalactites composed of the same substance.
The water in both springs, as it issues from the ground, is clear and bright in appearance, and almost tasteless. As yet it has not been chemically analysed, consequently its medicinal properties, if any, are unknown.
It may, however, be remarked that some of the best known mineral waters of Germany are altogether tasteless. In any case an analysis would prove interesting. I have twice carefully observed the temperature of the springs, once in July, 1882, and again in July, 1883. On both occasions the day was cold and overcast. The following are the results in degrees Fahrenheit:—
|July, 1882.||July, 1883.|
|Temp. of sea||44°||41°|
|" 1st spring||69°||67°|
|" 2nd "||73°||73°|
It will be observed that the maximum temperature obtained was the same on both occasions. Hence it cannot be due to any temporary increase of thermal activity at this place; but is probably to be attributed to the expiring heat of the volcanic agencies which formed the Lyttelton crater.