Edinburgh Castle on Its Volcanic Crag

Edinburgh Castle on Its Volcanic Crag is an original illustration set in Castle Rock, Edinburgh, Scotland. It lies in high latitudes, where the climate is oceanic — mild, wet through the year.

Edinburgh Castle forms a dark, irregular fortress silhouette on the flat summit of Castle Rock. Sheer black-gray cliffs fall toward green Princes Street Gardens, the crowded stone tenements of the Old Town trail eastward along one narrow ridge, and the ordered pale blocks of the New Town spread across lower ground beneath a cool changing sky.

Why does the fortress occupy a sheer rock at the head of one long urban ridge?

Castle Rock is the resistant core of an ancient volcano, and glacial ice streamlined softer ground behind it into a long protected tail. The fortress used the crag's steep faces for defense, while the medieval burgh grew along the only easy ridge leading away from the gate. Later planners crossed the valley to build a regular New Town on gentler ground, so the castle, fishbone Old Town and contrasting street grids all follow from the same crag-and-tail landform.

Terpano is a free daily geography puzzle. You study one original illustration, place a pin on a borderless terrain map, and see how close you were. There is no account and no sign-up; progress stays in your own browser. It plays in 11 languages.