...* As an instance of something of this kind I may, perhaps, be permitted to give a personal example. I had once been working hard, for about five weeks,...felstones, with large and irregular masses of intrusive greenstone, the exposed parts of each being frequent, but not continuous. Many a weary day had I climbed...

...Speaking afterwards about the difficulties of surveying and mapping the older Palaeozoic rocks, he says, " I had once been working hard for about five weeks,...made up of interstratified slates, sandstones, and felatones, with large and irregular masses of intrusive greenstone, the exposed parts of each being...