A little graphite is produced in Humboldt county.
Alexander von Humboldt (1769-1859) was the first modern geographer to become a great traveller, and thus to acquire an extensive.
The theory of geograph y was advanced by Humboldt mainly by his insistence on the great principle of the unity of nature.
Humboldt's concrete illustrations and the remarkable power of his personality enabled him to enforce these principles in a way that produced an immediate and lasting effect.
The treatises on physical geography by Mrs Mary Somerville and Sir John Herschel (the lattewritten for the eighth edition of the Encyclopaedia Britannica) showed the effect produced in Great Britain by the stimulus of Humboldt's work.