Squish. Squish. Squish. Squish. It was an unmistakable sound, although slightly out of context on such a bright, warm afternoon.

The saturated boots swinging leadenly on hikers legs announced that we were approaching the trailhead of the Zion Canyon Narrows.

This was southwestern Utahs Zion National Park from the bottom up.

Immense sandstone cliffs of gray and beige surrounded us, standing as if sentinels guarding the narrow river that had formed them.

We stepped into the trail, the North Fork of the Virgin River.

Water and sand rapidly filled our boots, and we saw and felt the forces that had started carving this canyon a million years ago. Having just paid the admissioin fee of cold feet and unsteady balance, we waded on to see more of the show.

Zion National Park is a work in progress. Its scale is immense. Long before it was added to the National Park System in 1909, its sheer, 3,000-foot cliffs, massive buttresses and deep alcoves offered shelter and sustenance to the Anasazi Indians (Navajo for Ancient Ones), who occupied Zion from AD 500 to about AD 1200. Following the sudden disappearance of the Anasazi, the Paiute Indians became the next residents of the area, until they were displaced by Mormon pioneers in the early 1860s.

Seeking to expand their economic, cultural and religious interests, leader Brigham Young ordered this area explored. When the first Mormon settler and farmer Isaac Behunin gazed across the canyon and sculptured rocks like natural temples of God, he was so moved by its grandeur that he called it Zion, after the biblical Heavenly City of God.

Zion soon became known through the work of artists, photographers and writers in the late 1800s and early 1900s. Designation as a national monument in 1909 and as a national park 10 years later brought greater accessibility. The Zion-Mt. Carmel Highway, including the Zion-Mt. Carmel Tunnel, was completed in 1930 and the motor tourists responded in ever-increasing numbers. After a day of exploring the splendors of the new park, the trail-weary motorist could relax in the rustic elegance of the the Zion Lodge, serenely located at 4,300 feet above sea level in the sheltering shadow of Red Arch Mountain.

Whoa! Its cold! I warned my wife and hiking partner, Abby, as we waded deeper into the North Fork of the Virgin River.

And slippery! Abby discovered.

With fanny packs slung around necks and cameras strapped well above waists, we carefully picked our way over smooth, melon-sized rocks under the swift current to reach the next sandbar.

Flash floods here are a real danger as the Narrows has walls 2,000 feet high but in places only 18 feet apart. In the 1960s, a sudden flood caught 26 hikers, drowning five. Consequently, rangers close the Narrows to hiking when flooding threatens.

When open, however, the Narrows offers a tremendous view of the effects of water and erosion. Although appearing quite clear much of the time, it is actually full of fine, suspended silt, enough to fill 30 dump trucks in a 24-hour period. It is estimated that a flood carries 2,000 times as much solid material. One hour of flooding will remove more silt, sand, and gravel than one year of normal flow. It is easy to understand how this relatively small river could carry so much earth and, over time, shape Zion Canyon.

The scenery began to change as we continued up the river. The sunshine that carried us to the trail head was mostly gone as the narrow walls around us seemingly speeded up the passing of day.

A coolness hung in the air that was contained within these walls. The narrowing canyon walls drew our eyes upward. The number of hikers decreased, our feet become heavier, and we paused, steadying against the current, and experienced a quite different world.

Zion is a geological masterpiece. In contrast to the Grand Canyon, where visitors gaze out from the rim, Zion is usually viewed from the bottom looking up. Its history is told in the sedimentary rocks layered one over the other in an orderly succession that began 240 million years ago. The oldest formations

are at the bottom, the youngest at the top.

The most important formation at Zion Canyon is the sculptured Navajo Formation, composed of red and white sandstone that forms the sheer walls of the park. The canyon started as a vast desert millions of years ago as winds blew one dune on top of another until sands reached a depth of 2,000 feet.

In the Narrows, a million years of flowing water then cut through this formation with very little widening. The canyon continues to be carved today. Rocks, weakened by fractures and joints, split off in long columns and leave smooth walls above. This process keeps the walls of Zion Canyon vertical. Hence, work in progress.

Our own progress was slowed by a growing concern of slipping and ending our run of good fortune and dry cameras. We left unexplored miles of watery trail ahead and decided to retrace our route out of the narrowness and into the sunlight. With more than 140,000 acres of differing elevations and land forms providing homes to 900 plant species and a variety of wildlife, Zion offered much more to see.

Most visitors to Zion enter at the East Entrance and follow the famous Zion-Mt. Carmel Highway onto the Zion Canyon Scenic Drive for a surprisely dramatic overview of the park.

Winding and steep, the roads will test your brakes but treat your eyes. Wind, water and time have carved symphonies of rhythmic patterns on the red, gray and beige sandstone walls throughout the park. Blue skies offer cool backdrops to the dry peaks that roll into view with every curve.

You may even experience the parks only traffic jam at the entrance to the 1 1/10-mile Zion-Mt. Carmel Tunnel. Todays oversized buses and recreational vehicles are too large for two-way traffic here, so rangers, like construction flaggers, direct a one-way flow of traffic.

The adventures extend well beyond the roadways. Zions 100 miles of wilderness trails and 23 miles of paved pathways ensure that everyone who visits the park will leave with a clearer understanding of the contrasts and dynamics of this canyon. The names of the trails in Zion QEmerald Pools, Hidden Canyon, the Narrows, Canyon OverlookQ suggest some of the surprises that lie beyond the road.

Desert plants that require very little water abound only a short distance from the lush vegetation growing beside the Virgin River.

Because of the porous nature of much of the parks rock, marvelous hanging gardens decorate many of the trails. Wildlife sightings are always an unpredictable delight. Mule deer, the colorful collared lizard and the common raven are but three of many species that call this park home.

As Zion Canyon is a desert canyon, visitors should always wear a hat and carry plenty of water when hiking. Since a stream may become a trail, hikers should have a pair of dry shoes back at the cabin or tent site.

The diversity of Zion doesnt end with the wildlife. Visitors to the park come in all ages and nationalities. One is as likely to hear Dutch or Japanese as English as visitors from around the world are drawn here in increasing numbers.

When the days exploring is done, the Zion Lodge and three campgrounds offer excellent accomodations within the park. Reserve early. Zions 2.5 million yearly visitors make reservations a must. Evening ranger programs offer education and entertainment. One recent presentation was cleverly entitled Sedimentary, my dear Watson. These regular gatherings also offer an excellent opportunity to share the days events with fellow adventurers. And as your day ends and you prepare to slumber, remember to set your alarm. The morning sun will be late to reach your cabin in the mountains shadows.

Not quite dry yet, I observed as I gathered our footwear in the morning. We shook out our boots and wrung out our socks, allowing the sand and water to continue their work creating Zion.