Why Are the Mecca Hills Striped? The Geology Behind the Red Hill Vista Hike
- Feb 20
- 18 min read
Updated: 2 hours ago
Red Hill Vista Hike Overview
Location: Mecca Hills Wilderness
Trail Type: Loop
Distance: 4.25 miles
Elevation Gain: 724 feet
Difficulty: Moderate
Hike Breakdown: Hike is suitable for a novice hiker who wants a challenge
Best Time: October–April
Highlights: Red hills, white bands, elevated bench views, ridge trails, and ancient mud cracks
TrailsNH Hiking Difficulty Calculator: 78

Click here to navigate to the TrailsNH website for a description of the hiking difficulty calculator.
Here is the aerial view of the hike route.

Why Hike Red Hill Vista
There are hikes where the destination is a summit, a waterfall, or a slot canyon, and then there are hikes like Red Hill Vista (red map pin) where the destination is an overlook that offers a rare top-down perspective of the terrain. Looking down, you see the unmistakable red hills and the mysterious white bands stretching across the landscape. On the Red Hill Vista trail, Mecca Hills geology is not just visible, it's unavoidable. During today's hike, we'll explain how these white bands formed and explore the geologic processes that shaped these hills.

Why Are the Mecca Hills Striped
The answer isn't available from the canyon and wash floor. It isn't until you climb onto the bench above the canyon that the landscape reveals a pattern shaped by soil formation and oxidation.
Want to understand what's really behind the pattern? Jump ahead to the Mecca Hills geology section for a closer look at how water movement, faulting, uplift, and erosion built these hills. 👉 Geology Section
Have a specific question in mind? Jump to the FAQ for quick answers about why the Mecca Hills are striped and what these white bands reveal about the landscape. 👉 FAQ Link
Let's Start Hiking
The trail begins in a gravelly wash located on Box Canyon Road (UTM Coordinates for the trailhead: 33.587222, -115.955000).

A Green Corridor in the Desert
At first glance, the wash leading to Red Hill Vista looks improbably lush, but this green corridor is no accident. A desert wash is a natural water-harvesting system. During rainy events, storm runoff funnels down these canyons, briefly turning the wash into a stream. The deep, sandy, and gravelly soil allows water to filter downward through the soil profile rather than evaporating. Beneath the surface, moisture can linger for days if not weeks.

Ground Cover and Low Shrubs
Storm runoff not only delivers water but also deposits a new generation of seeds. Washes function like natural seed conveyors. Seeds collected from slopes and canyons are swept downstream by flash floods, settling in concentrated patches as the water slows. However, most plants require more than a single flash flood to trigger germination. While flooding can disperse seeds and deposit them in fresh sediment, successful germination depends on a specific combination of conditions.

Seeds need adequate rainfall beyond the initial storm to keep the soil moist for an extended period, not just briefly wet. Cooler temperatures, typically in fall or winter, reduce evaporation and stress on young seedlings. The seeds also require consistent moisture over several days or weeks, allowing them time to absorb water and begin to grow.

In addition, they must be buried at the right depth. Deep enough to stay moist and protected from drying out, but shallow enough for the seedling to reach the surface.
Once these conditions are met, the seeds rapidly awaken, and wildflowers begin to sprout. Without this combination of conditions, seeds may remain dormant in the soil for years, waiting for the right moment in this unpredictable desert environment.

Perennial shrubs also respond to the pulsing rain events in the desert. These green cheesebushes are perfectly engineered for life in the disruptive wash environment. Adapted to thrive amid erosion and flash floods, cheesebushes dominate landscapes that are uninhabitable for many other plants. These adaptations include:
Flexible stems that bend rather than snap when floodwater or debris moves through a wash.
A shallow root system that anchors the shrub in loose sand while allowing it to survive partial burial; if sediment accumulates around the base, it can continue functioning rather than suffocating.
Rapid seed germination allows cheesebush to colonize washes before slower-growing woody shrubs arrive.

Canopy Vegetation
Desert ironwoods flourish in washes, utilizing deep roots to tap into consistent moisture and well-drained soil. These trees create a sheltered, 15°F cooler microclimate that protects young plants and seedlings from both extreme heat and colder temperatures.

Much like desert ironwoods, palo verde trees thrive in wash environments. They stand out with vibrant, photosynthetic 'green' bark. As drought-deciduous trees, they conserve water by dropping their leaves during dry spells, allowing them to utilize moisture and produce energy rapidly.

As the wash narrows into a canyon, creosote, lavender, and desert holly line the edge and slopes.



Entering the Zone of Fault-Shaped Chaos: Landscape Without a Pattern
As the green corridor fades into the background, the landscape tells the story of how the San Andreas Fault system has shaped every rock layer, ridge, and canyon you see ahead. The landscape is a tortured, chaotic mess of steep walls, deep gullies, and active, relentless erosion. At this bend in the wash, the earth stands almost upright.
The pale bands in this tilted rock wall were originally horizontal sediment layers of the Palm Springs formation, deposited between 2.58 and 0.76 million years ago by ancestral Colorado River systems as they flowed into the forming Salton Basin. Over time, the San Andreas Fault's compressive forces tilted the once-flat sediments into near-vertical slabs that dip sharply to the right at 60°–80°. Even today, these beds continue to be warped by the fault movement.

Not all sedimentary rock layers in the canyon are as tortured and tilted.

Heading deeper into the canyon, the rock face shifts, displaying a mottled, blotchy texture. This texture may have formed as slow-moving floodwaters deposited clay and silt, which later turned into weak sedimentary rock. These sedimentary rocks erode easily from the canyon walls, leaving behind a pockmarked, blotchy appearance.

At times, the canyon walls tower over Dave. The defining feature here is the distinct, brick-like horizontal bedding. Rather than forming from a single massive debris flow, this wall was built up by repeated flood events, each depositing a new layer and creating the stacked appearance.

Life on the Edge: Story of the Mecca Aster
One of the quiet surprises in this canyon is the prevalence of Mecca asters, which pop up in small clusters rather than in massive carpets. For much of the year, these plants look like ordinary, drought-stressed shrubs, making them easy for hikers to overlook.

If you're lucky enough to spot it, pause and recognize that this shrub is endemic to the Mecca Hills Wilderness, existing nowhere else on the planet.

Why the Mecca Aster Grows Only Here
The Mecca aster’s confinement to these hills is most caused by a combination of factors. It may be that Mecca aster is a soil specialist that thrives in fine sand and silt that is well-drained, nutrient-poor, and unstable. These niche conditions found along the wash margins and eroded slopes are inhospitable to most other desert flora.
Evolutionary isolation and limited seed dispersal may have played a role in restricting the aster to this small geographic region. The Mecca Hills are physically separated from major mountain blocks. In addition, its seeds disperse short distances, mostly falling near parent plants. Over time, a population of a broader ancestral aster may have become isolated and adapted to this very specific environment and eventually became a distinct species.

A Brief Season of Color
Mecca asters don’t always look drought-stricken. Their green-up period is tied to late winter and early spring measurable rain events, not just trace showers. A single storm rarely produces a strong display. It’s cumulative moisture that matters. Soil moisture must penetrate beyond the few inches. Light rainfall that wets only the surface won’t trigger much response. Also, like many perennials, they react to increasing daylight and temperature triggers (moderate highs during the day and cool nights), not just water availability.

By late winter, small, rounded buds begin forming and slowly unfurl as the days grow longer.

Typically, blooms appear in late February through April. The lavender petals and their golden center provide a sharp contrast to the surrounding beige terrain.


This is not a super bloom spectacle. At peak, each shrub may hold a dozen or so open flower heads at once. When you see them in bloom, you are seeing a species whose entire world is measured in miles, not regions.

As temperatures rise, the petals wither and curl. The central disk dries, and seeds mature within the head. The flower transitions from lavender to brown. By late spring, most seeds will disperse but settle close to the parent plant, reinforcing the species’ tight geographic range. By early summer, the leaves die off, and the shrub moves to a dormancy stage, awaiting the arrival of winter rains to begin again.

Vulnerability in a Warming Desert
Because the Mecca aster is endemic to these hills, its limited range makes it inherently more sensitive to environmental change than other widespread desert species. They would be unable to shift northward or upslope easily, so a single prolonged drought could potentially affect the entire population. After all, they have nowhere else to migrate if conditions deteriorate.
Mature shrubs are resilient and may be able to withstand periods of extreme drought, but vulnerability lies more with seedlings, where we could see a dramatic decrease in seedling establishment. Hopefully, these beautiful flowering shrubs are more resilient than we assume.

Following the Wash Beyond the Blooms
The Mecca aster life cycle is brief, but the story of these hills goes on.

A mile later, we turn left, leaving the open wash for a tighter path winding through a series of low, mottled, and blocky textured walls.

Where the Gully Tightens
Within ten minutes of joining the trail, the canyon walls began to narrow. Unlike the mottled surfaces seen earlier, this section features smoother upper rock faces, suggesting a more strongly cemented layer. Additional evidence of this durability is seen in the embedded pebbles (lower left), which are firmly held in place, and the large protruding boulder (lower right), which remains securely anchored in the wall. When an erosion-resistant rock layer like this restricts flow, storm runoff energy is directed downward, gouging a narrow, deep slot rather than a wide gully.

Over the next several hundred feet, the trail shifts between a narrow cut and a rocky slope. This change in shape occurs because flash floods are slicing through alternating layers of well-cemented and poorly-cemented sedimentary rock. Each layer erodes differently, so the canyon widens, collapses, narrows, and then flattens again.
Stepping Onto the Bench
The trail climbs out of the drainage gully onto a broad level expanse that geologists refer to as a ‘bench’. A bench is created when a resistant rock layer slows erosion, leaving behind a relatively flat, stable landform.

Benches are characterized by a 'rock armor' (small pebbles to fist-sized stones) that protects the ground from ongoing erosion. Nearby mountain ranges began shedding these rocks around 4 to 2 million years ago. Ancient rivers transported the fragments here, where they were incorporated into the sediment layers of the Mecca Hills.

Many of the cobbles scattered across the bench have a dark desert varnish, which is a paper-thin mineral skin built from windblown dust and microscopic life. It forms so slowly that a rock like this may have been sitting here for tens of thousands of years.

Despite the sparse vegetation on the bench, tucked beside a rock, we found this 3-inch-tall fishhook cactus, its bristling spines protecting a single bright red fruit. It’s one of the desert’s smallest but most stubborn survivors.

I had never seen a beavertail cactus with pads so wrinkled and ribbed. This unusual appearance is due to drought stress and severe desiccation from growing on the exposed bench. For comparison, the plant on the left, located in a nearby gully, displays the typical, fuller pads of a healthy beavertail.
View From the Bench: Where A Pattern Emerges
Benches are defined by their steep borders that provide sweeping views of the landscape. From this vantage point, the earlier chaos settles into structure. From here, the landscape reveals a clear, ordered pattern: alternating red hills and white bands extending horizontally across the terrain. What geological process created this?
Why Are the Mecca Hills Striped?
The Mecca Hills are striped because of resistant calcic horizons, layers of calcium carbonate formed within ancient soils, that have been exposed by uplift and erosion. As softer red sediments wear away, these hardened layers remain, forming white continuous white bands that shape how the hills erode over time.
A calcic horizon is a soil layer enriched with calcium carbonate that forms in desert environments when groundwater evaporates and leaves minerals behind. In the Mecca Hills, these hardened layers appear as white bands once they are exposed by erosion. Let’s explore these processes in more detail.
Red Hills: Where Sedimentary Rocks Rusted
In Mecca Hills geology, color is rarely random. These red hills are the result of iron oxidation, a chemical process that alters iron-bearing minerals within the sediment. Over time, several conditions worked together:
Iron-bearing sediment: Deposited millions of years ago, likely sourced from the ancestral Colorado River.
Exposure to oxygen: Uplift and erosion brought buried sediments to the surface
Wet–dry cycles: Intermittent moisture accelerated chemical weathering
Time: Longer exposure allowed oxidation to intensify
As iron reacted with oxygen, it formed iron oxides (such as hematite), producing the deep red coloration. In simple terms, the hills have undergone a natural form of rusting—similar to metal exposed to air and moisture, but over geologic time.

The intensity of red coloration increases near active fault zones in the Mecca Hills, where deformation alters how fluids move through the rock. This area lies within the fault damage zone associated with the nearby San Andreas Fault, where rocks have been heavily fractured.
These conditions enhance oxidation:
Mechanical fracturing: Breaks rock into smaller pieces, increasing surface area
Fluid pathways: Fractures allow water and air to move more freely through the sediment
Accelerated weathering: Increased fluid flow speeds up chemical reactions
Enhanced oxidation: Iron minerals oxidize more completely, deepening red coloration
Faulting does not create the red color, but it amplifies oxidation by increasing exposure and fluid movement.

The classic shredded badlands landscape, captured in this photo, is created by these weakly cemented red sediments and sedimentary rocks that break down easily in water.

The White Bands: Carbonate Accumulation and Bleaching
The white bands are not original sedimentary layers like mudstone and sandstone deposited by ancestral Colorado River systems as they flowed into the Salton Basin. They are calcic soil horizons formed by the accumulation of calcium carbonate after the sediments were deposited. However, their brightness is often enhanced by a second process: bleaching, which removes or alters iron pigments in the surrounding material.
Calcium to Carbonate: Building the White Bands
Rainwater dissolves calcium from the surrounding sediments.
Water carries calcium downward through the soil.
As the water slowly evaporates, the mineral precipitates and is left behind.
Calcium combines with carbonate in the soil to form subsurface layers, where calcium carbonate gradually accumulates.
Calcium carbonate acts as a natural cement. First coating individual grains, then forming small clumps, and eventually building into visible white bands of more strongly cemented layers known as calcic soil horizons.

Bleaching: Enhancing the Contrast
In addition to carbonate accumulation, some white bands are further lightened by bleaching, a process that leaches iron and other pigments from the surrounding red layers, leaving behind a paler, almost bleached zone. Bleaching doesn’t create the layer; it amplifies its visibility.

A Pause in the Landscape: How White Bands Form Over Time
Calcic horizons develop slowly, requiring extended periods of minimal erosion and little to no new sediment deposition. They reflect a pause in deposition, a time when the landscape was relatively stable; a rare occurrence in the constantly changing terrain of the Mecca Hills. Over thousands to tens of thousands of years, repeated wetting and drying cycles gradually create the distinct cemented white bands that we see today.
Exposed by Erosion: How White Bands Come Into View
Uplift and erosion gradually strip away the softer red sediments, carving into the hills and revealing these layers in long, continuous white bands across the landscape. What emerges are the more resistant calcic horizons, subsurface soil layers hardened by accumulated calcium carbonate.
Because these calcic horizons are more durable than the surrounding material, they don’t just appear as stripes; they actively shape the terrain by:
Forming benches and ledges along hillsides
Creating slope breaks where erosion slows or changes direction
Controlling long-term erosion patterns and hill shape

Walking along the trail, we noticed scattered fragments of the calcic horizons underfoot. While these layers are harder than the surrounding red sediment, they’re not immune to the elements. Over time, the desert’s extreme temperature swings cause the rock to expand and contract, while water seeps into cracks and gradually forces them apart until weaker sections of the layer break away.

Science in the Field
To verify that these fragments belonged to the calcic horizon, I performed a simple field test. Calcic soils contain abundant calcium carbonate, which reacts with acid by producing carbon dioxide gas. When I dropped a small amount of dilute hydrochloric acid onto the surface, it fizzed as CO₂ was released.

Why the Pattern Only Appears From Above
The striped pattern disappears at ground level because it depends on scale. From the wash floor, you’re surrounded by individual slopes and isolated layers, all too close to see how they connect.
However, when you step onto the bench, your perspective shifts. The red hills and white bands align across the landscape, revealing continuous stripes that only emerge when the terrain is viewed as a whole from above.
Why Don't All Mecca Hills Have Stripes
These patterns do not appear everywhere in the Mecca Hills because their formation requires precise alignment of conditions:
Sufficient calcium in sediments
Intermittent groundwater movement
Strong evaporation
Stable surfaces long enough for soil horizons to develop
Without this combination, the white bands either never form or remain too faint to be exposed
Walking Along the Spine
As we hike further, the broad bench gradually tapers into a series of narrow, winding ridges. Geologists use the term 'lithologic interfluve' to describe a resistant rock ridge that is situated between two distinct washes. The slope on both sides of the ridge easily erodes and deepens while the ridge stands firm.

Small differences in sediment, cementation, and drainage can cause ridge widths to vary dramatically over short distances. Where the trail crosses a more resistant layer, the ridge stays stable and offers a wider walking surface.

When the interfluve crosses a soft or poorly cemented bed, the path quickly tapers. Because erosion occurs simultaneously from both slopes, the softer layer is cut back more rapidly than the harder cap above it. As the slopes retreat toward one another, the ridge tightens into a slender spine of sediment separating the two washes.

Given enough time, erosion will turn the interfluve into a knife-like ridge that inevitably collapses and renders the path impassable. All the more reason to hike Red Hill Vista sooner rather than later.

We continued to follow the ridge until we reached a large rock cairn. It’s a great spot to rest and enjoy the views.

Leaving the bench and interfluve behind, the route drops back to a major wash through a small drainage gully that's located close to the rock cairn.

Retracing the Work of Erosion - Returning to the Wash
The terrain begins to reverse the sequence we experienced on the climb to the bench.
The trail winds through layers of sedimentary rock that alternate between weaker and more resistant rock strata. This steep wall consists of weakly cemented mudstone and silt that is currently undergoing active erosion. The narrow vertical grooves running down the slope are called rills. They form as rain and runoff cascade down the slope. Each rill concentrates runoff, carving deeper grooves over time.

Shortly after leaving the bench, the trail cuts directly through a calcic horizon where we can clearly see how the calcium carbonate cement protects it from erosion.


Tall canyon walls often form through differential erosion, where layers of sediment with different strengths weather at different rates. Stronger cemented beds (area between the green lines) erode much more slowly than the softer silts and mudstones sandwiched above and below. These more erosion-resistant beds act like structural ribs within the cliff face, helping maintain the height and steepness of the canyon walls even as the softer material above and below continues to erode.

Even the vegetation reflects the landscape’s structure. A tamarisk tree clings to the raised section of the wash, its roots laid bare by erosion and its survival uncertain. Life takes hold, but erosion continues to cut deeper.

A mile into the wash, the scenery shifts back to the tan Palm Springs Formation similar to those we saw at the beginning of the hike.

Fossilized Mud Cracks: A Desert Floor Turned Upside Down
Near the end of the hike, we came across another unique geologic feature: an overhead rock outcrop with well-preserved mud cracks. This erosion-carved opening along the trail exposes a mudstone layer, circled in red, where the mud cracks formed millions of years ago.
The lower rock unit beneath the mud cracks is a well-cemented, durable sandstone, while the upper unit, where the cracks formed, is a weakly cemented mudstone. Although the sandstone is stronger, the contact between the two layers is the natural weak point, so it’s not surprising that a major fracture has occurred here, exposing the ancient mud cracks.

What Are You Seeing
Looking up at the ledge, it takes a moment to recognize these aren’t random fractures but ancient mud cracks suspended, locked in time for 2-4 million years. They didn’t form above us. They formed on an exposed, drying mud surface, such as a floodplain, playa, or quiet basin. In other words, we’re not looking at a ceiling; we’re standing beneath a former ground surface. As the mud dried, it contracted and split into polygonal shapes. Later, new sediment buried this surface, protecting it. The cracks themselves were filled with sediment or minerals (now seen as darker lines), which helped preserve the pattern.
How It Ended Up Above You
Over time, the buried sediments hardened into rock. Tectonic forces later tilted and uplifted these layers. Erosion then carved into the hillside, exposing the mud cracks from below, so today, we are standing under an ancient land surface.

Metal and Mesquite: An Unexpected Desert Ending
Further down the canyon, we found this rusted car body. Desert dumping of cars is way too common, and I don't understand the motivation behind it.

Just before reaching the end of the trail, we passed through a stand of honey mesquite, a fitting close to a hike defined by outstanding Mecca Hills geology and remarkable desert flora.

Snapping a quick photo to remember another incredible hike through the Mecca Hills.

Trail Takeaway
The Red Hill Vista hike isn’t just a loop through colorful terrain; it’s a chance to see a cross-section of Mecca Hills geology. The red slopes record ancient sediment laid down in shifting basins, while the white bands mark long pauses where minerals slowly built beneath the surface.
The striped hills are not just visually striking; they reveal how water once moved through the soil, leaving behind mineral signatures that still shape our views of the hills today. By the time you finish the hike, the pattern isn’t just something you see, it’s something you understand. Because once you learn how to read this landscape, every hike here becomes something more.
How to Read the Landscape
🔴 RED = Deposited Sediment
Carried by Water & Left Behind
Rusty or brick-red color
Found in canyon bottoms or clustered hills
Softer, often crumbly
Builds up in low-energy areas
⚪ WHITE = Calcic Horizon
Formed Underground & Later Exposed
Bright white or pale
Runs across slopes as continuous bands or stripes
Harder sometimes cement-like
Exposed when erosion cuts into the hills
These white stripes are just one chapter in a much bigger geologic story, one driven by shifting faults and relentless erosion. Follow the trail deeper to see how it all comes together.
Step into Skeleton Canyon and the story changes; you're no longer just seeing the deposited layers but hiking along the fault zone itself.
Explore the Twisted Canyon Mecca Hills hike for tighter bends, layered walls, and a more immersive look at the folded terrain.
Red Hill Vista FAQs
These striking white bands raise common questions about how they formed, and what they reveal about the processes that shape the Mecca Hills.
What causes the white stripes in the Mecca Hills?
The white stripes in the Mecca Hills are calcic horizons, layers of calcium carbonate that formed within ancient soils. As mineral-rich water moved through the ground and evaporated in this desert environment, calcium carbonate accumulated and hardened over time. Uplift and erosion later exposed these layers as continuous white bands across the hills.
Why do white bands only appear in certain canyons?
White bands appear only in certain canyons because calcic horizons form under specific conditions and are exposed unevenly. They develop in stable areas with minimal erosion, then become visible only where uplift and erosion cut into the hills at just the right depth. In other areas, they remain buried or never formed at all.
What is a calcic horizon?
A calcic horizon is a soil layer enriched with calcium carbonate that forms in arid and semi arid environments. It develops as a mineral-rich water moves through the ground and evaporates, leaving calcium carbonate behind to accumulate and harden over time. Once exposed by erosion, these layers appear as white bands in the hillside
Are the white bands a separate rock layer?
No, these white bands are not a separate deposited layer. They formed after the original sediments were laid down, as part of soil development (a pedogenic process). This means they are better understood as altered zones within the rock, not distinct sedimentary beds.
Did water create the white layers?
Yes, but not in the way a lake or river deposits sediment. Instead, groundwater moving through the soil dissolved calcium and redeposited it as the water evaporated, gradually building up these mineral layers.
Are the white bands related to the San Andreas Fault?
Indirectly, yes. The San Andreas Fault system uplifted and fractured the landscape, exposing these buried soil horizons. Without tectonic activity, the bands would likely remain hidden beneath the surface.
How can you identify a calcic horizon in the field?
Look for a white or pale hardened layer that stands out from the softer surrounding sediment. calcic horizons often form continuous bands across slopes, create small ledges, and feel firm or cemented due to calcium carbonate binding the grains together. Return to Science in the Field for a simple test to detect calcium carbonate
How long does it take to build calcic horizons?
Calcic horizons usually take thousands to tens of thousands of years to form. Their development requires long periods of minimal erosion, allowing calcium carbonate to accumulate gradually as water moves through the soil and evaporates. Well-developed horizons can represent extended intervals of landscape stability.
Why do some canyons have red hills while others have white bands?
Red hills and white bands form under different conditions and appear where those conditions are best preserved and exposed. Red hills develop in low-energy canyons where iron-rich sediments accumulate and oxidize over time. In contrast, white bands mark calcic horizons, which are calcium carbonate layers that form within stable soils and are only visible where erosion has cut into the hills at the right depth
What is the relationship between the Mecca Hills Wilderness and the Chuckwalla National Monument?
Stretching across more than 624,000 acres of the Colorado Desert in Southern California, Chuckwalla National Monument protects one of the most geologically dramatic landscapes in the American desert. Established in 2025, the monument links a vast network of mountains, desert valleys, and historic travel routes that stretch from the Mecca Hills eastward toward the Chuckwalla Mountains near the Arizona border.
While the entire monument is impressive, the Mecca Hills offer a unique display of tectonic forces colliding with erosion. The hills lie directly along the San Andreas Fault system, one of the most famous faults on Earth. Over millions of years, the relentless grinding, bending, and fracturing of the Earth's crust along the Pacific and North American plate boundary has forced thick layers of sediment upward, sculpting the rugged landscape of the Mecca Hills. This region is one of California's most accessible locations to get a firsthand look at the immense power of plate tectonics.

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