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About Us

At El Potrero Chico Guides, we're committed to providing you with a thrilling and unforgettable adventure. Our parent company, Sierra Climbing School LLC, has been in the business for years, and we are proud to be owned and operated by an AMGA certified rock guide, Mark Grundon. We believe that it is important to have the highest trained and most knowledgeable guides in the industry, so you can have an enjoyable and safe experience climbing the incredible Potrero Chico.

Mark Grundon

Mark has been guiding from Alaska to Colorado for the last 16 years. He also currently splits his time between Yosemite National Park and El Potrero Chico.  He also guides trips on Mexico's volcano Pico de Orizaba. He recently retired from ski patrol after seven winters to follow his deeper passion: climbing. Mark is a strong believer in “living the dream”, and following your passions whatever they may be. Mark enjoys sharing a rope with everyone from Yosemite rock stars to first time climbers. He has guided 7 successful summits of El Capitan. He has made one day ascents of El Cap and Half Dome in Yosemite. Mark has his EMT, a Leave No Trace trainer certification, is an Assistant AMGA Single Pitch Instructor Provider, AMGA Apprentice Alpine Guide, and AMGA Certified Rock Guide.

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Heather Smallpage

Heather (they/them) grew up in the flatlands of Wisconsin, and moved out west to pursue their passion for mountains as soon as they could. Since then, Heather has climbed and guided throughout the United States.They are a part of the queer/LGBTQ+ community and their experiences navigating rocks and the climbing community, while also their own identity remains to be a beautiful challenge. Wherever their adventures take them, Heather continues to develop a deep love for this activity and the places it takes them. Over the years, Heather has completed multiple ascents of big walls in Yosemite, including a number of routes on El Cap. They are most drawn to the art of rope-soloing, having climbed walls in Zion and Yosemite by themselves. Despite their achievements, one of Heather's biggest goals as a rock climber isn't about how hard they can climb, but about creating a space where all can feel welcomed, able to learn without judgment, and empowered in their bodies and minds. Heather believes that climbing can create a sense of connection - within ourselves, our climbing partners, and with the world around us - and takes great comfort in all the lessons we can learn from tuning into ourselves as part of the world. They are an AMGA Apprentice Rock Guide, Wilderness First Responder, and Leave No Trace Educator.

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Alex Moss

Alex has always loved climbing of any sort, and fell in love with rock climbing at a young age through a climbing team in South Carolina. Since studying Outdoor Leadership at Warren Wilson College, he has loved helping people learn and play in the outdoors in many ways. After moving out west, he has broadened his skills from gyms and single pitch climbing to adventure climbing on high walls and peaks. Alex is motivated by climbing in new places, exploring new styles of climbing, and finding flow in new movements. As a guide, Alex aims to empower people by teaching new skills and encouraging them to do things they didn't know were possible for them. Alex also enjoys dance, absurdity, reading, and cooking with friends. Alex is an AMGA Apprentice Rock and Alpine guide and Wilderness First Responder. 

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Lani Chapko

Lani is an AMGA Certified Rock Guide from Index, Washington. She has spent the last 5 years climbing and guiding all over the West Coast of the US. A love of mixing climbing and travel has taken her to Ecuador, Argentina, Chile, Nepal, Mexico and Canada. She enjoys all forms of climbing but finds her fullest expression of the sport to be on long adventurous routes and big walls. She has put up first ascents in Washington and Red Rock. Lani has a degree in engineering, and enjoys nerding out about gear and systems. She is also AMGA Assistant Alpine Guide, Wilderness First Responder, and Leave No Trace Trainer. Lani loves sharing the sport that has brought her so much joy with others. Looking forward to getting to know you in the great outdoors!  

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Sam Boyce

 Sam grew up in the foothills of Washington state, in the heart of the Pacific Northwest. Here, he developed a keen sense of adventure and stoke for anything climbing.  Sam's specialty is in the world of Big Wall climbing. He has climbed dozens of big wall routes including numerous ascents of El Capitan, ranging from 1 day to 8 days. His passion is adventure climbing, and in particular doing first ascents. He has pioneered new routes of every style, from single pitch sport climbs, to big bold trad lines hiding in plain sight, to heavy duty backcountry big wall aid climbs. He started instructing and guiding in 2015 and has worked full time as a Rock and Alpine guide ever since. Sam is a Wilderness First Responder, a Leave no Trace Trainer, is a Certified AMGA Rock Guide, and an AMGA Assistant Alpine Guide.

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Pete Fasoldt

Originally hailing from Maine, is a certified AMGA Rock Guide. He has worked as a ski patroller, as first mate on sail boats and as the owner of a rock guiding outfit in Acadia National Park. Pete now works as a rock and alpine guide throughout California's Sierra Nevada from the Lake Tahoe area down into the High Sierra and in Mexico in the winter season. Pete has put up many new routes including a ten pitch 5.12+ route in the nearby La Huasteca Canyon. He has climbed all over the world including ascents of the Trango Towers.

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Adam Mitchell

Adam has been guiding in El Potrero Chico for years.  He is an AMGA Rock Guide and will be taking his exam soon.  He is an AMGA Single Pitch Provider and runs a climbing school in Texas at Enchanted Rock.

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