VOLCANIC ACTIVITY AT MOUNT TRIDENT, Katmai National Monument. In 1912 Alaska's Mount Katmai was a prominent and peaceful landmark. Then a series of frightening earthquakes was followed by a great flow of incandescent sand that welled up through fissures in the valley floor and flowed for 15 miles, consuming glaciers, trees, grass, and all living things in its path. Thus was born the Valley of Ten Thousand Smokes. Shortly afterwards a series of gigantic explosions from the top of Mount Katmai carried the same type of effervescent rock high into the stratosphere, to fall into and choke harbors for miles around. Then quiet came again, and the "smokes" all but died away. Occasionally one or another volcano would show slight activity, and in 1953 Mount Trident, shown here, and three other volcanoes—Mageik, Martin, and Novarupta all erupted. As to the future, who knows?

TEMPLE OF THE SUN, Carlsbad Caverns National Park. Carlsbad Caverns are the largest underground chambers yet discovered anywhere—a series of connected underground caverns with countless magnificent and curious formations carved far underground in limestone by running and dripping water. The Big Room, where the Temple of the Sun may be seen, is the most majestic of the many caverns. At one point its ceiling arches 285 feet above; and the trail around its perimeter is 1-1/4 miles long. Trips covering 2-3/4 miles of trail (if the visitor leaves the caverns by the new elevators which have replaced inadequate old equipment) are conducted daily. If he walks out—and up—add another mile to cover the 754-foot climb to the entrance. The temperature in the caverns is a constant 56°. A lunchroom is located just outside the Big Room.