Celebrating 5 years of the Irvine Ranch as a National Natural Landmark with a private tour to Limestone Canyon and the Sinks


Limestone Canyon Wilderness Area: Hicks Haul-Loma Ridge-Limestone Canyon Loop to the Sinks

Date Hiked: October 10, 2011*
Best Season: Autumn Spring Winter
Check Trail Conditions: Irvine Ranch Natural Landmarks. Questions & information: Irvine Ranch Conservancy (714-508-4757).
Notes: *We're listing this as a hiking trail, but we did a cushy guided driving tour. Limited public access. Self-guided hike/bike tours available monthly. Park-guided activities weekly. Outhouses only.
  • Distance: 9.9 miles round-trip
  • Elevation Gain: 903 feet
  • Route Type: Loop
  • Trail Type: Paved, dirt single-track & fire road
  • Difficulty: Moderate

We had the privilege today of attending a private tour and photo-op set up by the Irvine Ranch Conservancy (IRC), exclusive to local Orange County bloggers, to celebrate the fifth anniversary of the designation of the Irvine Ranch as a National Natural Landmark (NNL).  When Jeff and I received the invitation last week, we both immediately put in for a vacation day from our full-time day jobs to take advantage of this unique opportunity.

Although we did this loop as a cushy guided truck tour, our interpretive guide indicated that it makes for an excellent scenic hiking or biking trail on one of the days the Wilderness Area is open for self-guided activities.  So, we are still listing this under hiking and biking options (just not counting it in our own mileage), and hope to retrace the route on foot again with friends.

Limestone Canyon Wilderness Area

The Augustine Staging Area.

Limestone Canyon Wilderness Area

Ed, Evelyn, and Wida brief us on the tour.

Limestone Canyon Wilderness Area

Ed kindly helps me up into the open air 4X4 tour truck.

National Natural Landmarks (NNL) Program

The NNL Program falls under the jurisdiction of the National Park Service, and was established in 1962.  Lands that receive this designation by the Secretary of the Interior are recognized as having “…some of the best examples of biological or geological resources in the nation.”

Nearly 40,000 acres of Irvine Ranch open space has been designated both a national and state natural landmark.  Our fabulous interpretive guide, Evelyn, advised that the IRC partnered with the Department of Geological Sciences at California State University, Fullerton (my employer) to apply for and obtain NNL designation.

Because the emphasis of the Irvine Ranch Natural Landmarks is on preservation and stewardship of geological and biological resources, its open spaces are not officially open to the public like regular parks.  However, the IRC sponsors two self-guided “public” days each month — Open Access Days at Limestone Canyon, and Wilderness Access Days at Bommer Canyon — as well as an exhaustive schedule of daily guided activities throughout Ranch open spaces for all ages, interests and fitness levels.  The Irvine Ranch NNL receives approximately 5,000 visitors on an average month, with the two “public” days each month accounting for 20% of this traffic.

Limestone Canyon Wilderness Area

The first leg of our tour is along the paved and popular Hicks Haul Road, which becomes Jeffrey Road in Irvine.

Limestone Canyon Wilderness Area

Ed turns off Hicks Haul Road on to the single track Loma Ridge Trail. That is the UCI research center in the middle.

Limestone Canyon Wilderness Area

Our interpretive guide, Evelyn, points out natural formations, vegetation and wildlife along the way.

Limestone Canyon Wilderness Area

Ranger Adam follows along in his OC Parks truck, keeping an eye on things and making sure we're safe.

About the Irvine Ranch

Having lived in Orange County since I was about five, the Irvine Ranch and the Irvine Company are names with which I grew up.  Their origins can be traced back to 1864, when James Irvine I purchased 120,000 of ranch lands with two partners that he later bought out. His son, James Irvine II incorporated the landholdings and ranch as the Irvine Company in 1894.

It was James Irvine II who gifted our newly formed county with its first county park when he sold Orange County Park (later renamed Irvine Regional Park) to the Orange County for $1 in 1897.

About Limestone Canyon Wilderness Area

Limestone Canyon, the heart of the Irvine Ranch, is located in a protected area between the Loma Ridge foothills and the Santa Ana Mountains. Although much of the park is quite exposed, it does include many groves of sheltered oak trees (mostly coast live oaks), as well as two separate year-round natural water sources. Mountain lions and deer call this area home, however Evelyn noted that this is the first year to witness a full recovery of deer since the Santiago Fire in 2007. Horned lizards, bees, snakes, and raptors are quite plentiful as well. Poison oaks is the only poisonous plant. And much of the land is dedicated to grassland restoration.

Tour Logistics

We met up at 9:30am at the Augustine Staging Area in Limestone Canyon Wilderness Area, located on Santiago Canyon Road just southeast of Irvine Lake.  There we were greeted by Wida Karim (Communications Manager, IRC), Evelyn Brown (Interpretive Specialist, IRC) Adam Shuck (Park Ranger, Orange County Parks), Ed (volunteer driver extraordinaire, IRC), and Lyndie Bradshaw (Outreach Specialist, REI Orange County).

After brief introductions and a quick overview of the tour, we joined three other local bloggers, a former Irvine Ranch resident, and Orange County historian and author Phil Brigandi (a colleague of mine), by piling into the back of a canopied Ford F-150 for an open air off-road adventure tour.  Jeff and I were more than thrilled to discover that we were going to get to ride in the back of a truck instead of in a bus or SUV.  Volunteer extraordinaire, Ed — who hasn’t set foot back in an office since retiring from a career spanning more than a quarter of a century with Xerox — did the driving, and our guide Evelyn sat in back with us narrating and pointing out wildlife and points of interest.

Limestone Canyon Wilderness Area

Stopping at a scenic lookout on Loma Ridge Trail.

Limestone Canyon Wilderness Area

Sweeping vistas of Orange County (and Catalina): from Fashion Island on the left to the Tustin blimp hangers on the right, and Disneyland (not in this photo) to the far right.

Limestone Canyon Wilderness Area

A look in the opposite directions provides stunning views of the Santa Ana Mountains, and Silverado Canyon.

Limestone Canyon Wilderness Area

Volunteer extraordinaire Ed shares a story.

Route and Features

From the Augustine Staging Area, we proceeded up Hicks Haul Road, an old ranch road that had been paved to provide access to Irvine Lake and the mines in Black Star Canyon.  It is now used primarily as a more direct staff access route from IRC headquarters (Hicks Haul Road becomes Jeffrey Road in Irvine), as well as an access route to the nearby climate change research center managed by UC Irvine.  However, its paved surface also makes this road popular with fitness hikers and folks publishing strollers on public-accessible days.

Limestone Canyon Wilderness Area

Our shady picnic spot next to Box Springs.

Limestone Canyon Wilderness Area

We spent a couple minutes of silence soaking in the serene sounds of the area.

Limestone Canyon Wilderness Area

A lunchtime guest.

At the research center, we headed off-road up a narrow, windy, and sometimes bumpy, single-track road called the Loma Ridge Trail. I imagine this trail is extremely popular with mountain bikers on Open Access Days. At the top of the trail, Ed stopped and parked a while so that we could take in stunning views of central Orange County (including Disneyland and the Tustin blimp hangars), as well as Fashion Island, the coast and Catalina Island. Evelyn says that downtown Los Angeles and the Hollywood sign can be seen from here on clear days. Peering in the other direction provided us with excellent views of Silverado Canyon and the Santa Ana Mountains.

From this brief stop, we proceeded along Loma Ridge Trail to a beautiful secluded shady oasis along Box Springs (also knows as Bolero Springs), where IRC treated us to a peaceful enjoyable picnic lunch.

Limestone Canyon Wilderness Area

The drive down Loma Ridge Trail -- our first look at the Sinks.

Limestone Canyon Wilderness Area

The spectacular Sinks -- Orange County's Grand Canyon.

Limestone Canyon Wilderness Area

Enjoying the scenery from the new viewing platform. Evelyn advised that we could get actually get a cell data signal here for those of us who wanted to check in to Foursquare!

The final stop of the tour took us to the magnificent geological formation known as the Sinks, frequently called the “Grand Canyon” of Orange County. Unlike the actual Grand Canyon, though, the Sinks were formed by a single geological event. If you’ve ever visited Red Rock Canyon in nearby Whiting Ranch Wilderness Park, the Sinks look quite similar. But, the canyon also reminds me of a smaller version of the Devil’s Punchbowl. Hiking in the canyon formation itself is prohibited for safety and ecological reasons due to its soft sandstone structure. But, on Open Access Days and guided outings, hikers can enjoy the trail that goes all around the exterior of the canyon. Because vegetation in the Sinks is much more sparce than the rest of the Wilderness Area, the canyon provided a refuge to much of the park’s wildlife during the 2007 Santiago Fire.

Limestone Canyon Wilderness Area

Making the return trip along Limestone Canyon Road, a flat fire road dotted with shaded canopies of trees.

Limestone Canyon Wilderness Area

We saw quite a bit of deer, -- or at least the same herd repeatedly, along the drive. Always majestic to behold.

From the Sinks, we hopped back in the truck and followed Limestone Canyon Road back to the Augustine Staging Area. This dirt road is quite popular with park visitors because it is flat and fairly well shaded. It is the route most foot travlers take to hike to the Sinks.

Limestone Canyon Wilderness Area

The Conservancy thinks this plateau along Santiago Canyon Road is the site of a former Native American settlement because of how bare it is of trees.

Limestone Canyon Wilderness Area

Testing the ability to grow native grasses to eventually replace non-native species and restore indigineous ones.

Limestone Canyon Wilderness Area

Making the final approach to the Staging Area.

What Now?

We hope you feel inspired to visit one (or more!) of the Irvine Ranch Landmarks. And, if you feel the need to give back and help steward our natural resources, the IRC holds four volunteer recruitment events each month to add to its already impressive ranks of approximately 300 volunteers.

We deeply appreciate the show of media partnership extended by the IRC to local bloggers, and we look forward to visiting more Irvine Ranch Natural Landmarks in the future — even without our beloved Beagle (since dogs are not allowed on most of the Irvine Ranch Natural Landmarks).

View Limestone Canyon Wilderness Area: Hicks Haul Road-Loma Ridge Trail-Limestone Canyon Road Loop in a larger map

Limestone Canyon Wilderness Area Elevation Chart

Click on the image for a larger view of the elevation chart.


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