[lurker]

Within two days drive and into Northern Mexico we have the Crystal Cave of the Giants and the Copper Canyon.

From a website:

Found deep in a mine in southern Chihuahua Mexico, these crystals were formed in a natural cave totally enclosed in bedrock. When I first stepped into the cavern it was like walking into the Land of the Giants. I have often admired crystal geodes held in my hand, but when photographing these unique natural structures it was almost impossible to get any sense of scale. This is a geode full of spectacular crystals as tall as pine trees, and in some cases greater in circumference. They have formed beautiful crystals that are a translucent gold and silver in color, and come in many incredible forms and shapes. Some of the largest are essentially columnar in shape and stand thirty to fifty feet high and three to four feet in diameter. Many of the smaller examples are four to six feet in circumference, have many incredible geometrical shapes, and probably weigh in excess of ten tons. The columnar pillars are at first the most striking shape, but later I noticed there were thousands of "sharks teeth" up to three feet high placed row upon row and dispersed at odd angles throughout the caverns. While some of the crystals are attached to the ceiling walls and floors of the cave as might be expected, some exist in great masses of spikes and almost float in air. These crystals seem to defy gravity, as they must weigh several tons.

Example:


In the same area is the Copper Canyon.

There are nine major canyons: Urique, Sinforosa, Batopilas, Candamena, Mayo and Huapoca, Chinipas, Septentrion and Oteros. In the United States of America, we tend to view the Grand Canyon as a truly massive feature of the earth. Yet in northern Mexico only 200 miles south of the US border, lies a system of canyons that humble the mighty Grand Canyon. The deepest, Urique, is a total of 1,879 meters.

About 18,000 Google images.