Notes on the new Hobart storage reservoir

As the New Storage Reservoir will probably be completed before the next evening meeting of the Royal Society, I submit some remarks upon the geological conditions of the locality, based upon notes made at various times during the progress of the works. In a paper read before the Society on the 11th of September, 1877, on the causes of the failure of the dam of the old reservoir, I mentioned incidentally that another fault, in addition to those then under consideration, crossed the valley of the Sandy Bay Rivulet close to the upper end of the reservoir. In the following year I visited the place in company with the members of the Waterworks Committee to inspect the site selected by the Corporation Engineer for the dam of the proposed new reservoir, on which a good deal of work had already been done, and which proved to be at that part of the valley which I had described as being traversed by a great fault. A cutting had been made into the mudstone rock on both sides of the rivulet, and a shaft sunk to a depth of about 40 feet in its bed, with the object, I believe, of ascertaining whether the character of the rock was such as to serve for a good foundation ; but all the information thus obtainable might have been readily gathered from an examination of a few of the sections exposed in road cuttings or otherwise, where an opportunity is afforded of studying a far greater thickness of the beds of the mudstone series.