Day Trips

National Natural Landmarks are some of the country's most unique biological and geological sites. Founded in 1962, the NNL designation recognizes both public and private resources that have specific natural features. These are the best examples of a vanishing wilderness.

By joining the list – 586 have so far – the owner voluntarily works to conserve the rare ecosystem on their property. The National Park Service administers the list. One-third of the landmarks on the list are privately owned.

What is surprising is what's not on the list. You won't find the Grand Canyon, because for all its beauty, the canyon is not a unique environment. If you visit all 586 sites, you will see exceptional scenery and a cross section of the nation's natural history.

Of the 48 states and territories with sites, California has the most with 35 landmarks, and Texas has the sixth-highest number with 20. The largest NNL in Texas, at more than 16,000 acres, is Palo Duro Canyon State Park, while the smallest is the 2-acre, privately owned Ezell's Cave.

Of the NNLs in Texas, five are caves. Ezell's Cave, outside of San Marcos, is owned by the Texas Cave Management Association. Because of the rare and endangered species that live there, it is not open to the public. Visitors are welcome at Cave Without a Name in Boerne, Caverns of Sonora in Sonora, Longhorn Caverns near Burnet, and Natural Bridge Caverns south of New Braunfels.

Devil's Sinkhole outside of Rocksprings is the largest single-chamber cavern in Texas. To reach it, you must join a tour offered by a private group, although the property belongs to the state. Millions of bats emerge from the hole on summer evenings.

Also on the NNL list are some of Texas' most unusual natural features. Enchanted Rock State Natural Area, north of Fredericksburg, was added in 1970. The fall foliage of Lost Maples State Natural Area made the list, as did the dinosaur tracks of Dinosaur Valley State Park. The Odessa Meteor Crater is the only Texas county park on the national list.

The federal government has 39 units in Texas including national parks, forests, wildlife refuges, historic sites, and grasslands, but only five are on the NNL list. The Fort Worth Nature Center and Refuge is the only Texas municipal park included. Of the sites in Texas, only two are not open to the public.

The list is not only a good place to start for day trips within Texas but also a good way to find hidden gems in other states. New Mexico has 12 sites on the list, including the Mescalero Sands South Dune. Arkansas' Mammoth Spring is the second-largest spring in the Ozark Mountains and one of five NNL locations in the state.

As you're planning your next trip, look up what national treasures might be nearby. The list and more information can be found at www.nature.nps.gov/nnl/nation.cfm.

1,035th in a series. Collect them all. Day Trips, Vol. 2, a book of "Day Trips" 101-200, is available for $8.95, plus $3.05 for shipping, handling, and tax. Mail to: Day Trips, PO Box 33284, South Austin, TX 78704.