The Porphyry District of Lugano, West of the Valganna

During an excursion to the South of Switserland, Professor Escher suggested my mapping out the south-western corner of the porphyry district of Lugano. I gladly agreed, for his detailed examination of the Morcote-peninsula had already shown that many interesting facts had escaped unobserved during the small-scale mapping forty years ago; and it was, therefore, highly probable that the projected work would prove fruitful. The necessary field-work was carried out in the spring of the years 1924 and 1925. The collected material I examined in the geological museum of Leiden, where it will remain in future.