XXIII. On the Stream Works of Pentowan.

Abstract

When, a little time back on a mining excursion in the district of St. Austle, my avocation for the first time called me to visit a stream-work in that neighbourhood, I was so struck with what I saw, that I employed a second day from morning to evening in a most scrupulous examination of one of the works, from a wish of communicating my observations to the Geological Society. The works that I visited are called the upper and lower Pentowan Stream Works, and are situated on the river which flows from Hensbarrow Hill by St. Austle, and enters the sea about three miles and a half south of that town, and at about the same distance north of Chappel Point, after a course of somewhat more than eight miles. I calculate the elevation of Hensbarrow Hill at 900 or 1000 feet above the sea; from thence to St. Austle the descent of the ground being very rapid the river is precipitated over many considerable rocks, and during the rainy season may be considered as a succession of cascades. In the dry season there is but little water, but after sudden rains the rise is both rapid and dangerous. Small rounded pebbles are found all the way in this part of its bed. From St. Austle to the sea the descent of the land is very gentle, and the hills running north and south on each side of the river seem to direct its course. In some places these approach