⏵ Course guide · Massachusetts North Shore loop race
Stone Cat sends every distance, from the 10K up to the 100K, around the same rolling 12.5-mile loop through Willowdale State Forest, roots and rocks under fallen November leaves, with a hard 14-hour course close. I will walk you through the loop and cutoff structure first, then give you a pacing and fueling plan built for repetition rather than one defining climb, plus free tools to dial in your own numbers.
These facts come from the official trailanimals.com event and course pages. TARC logistics can shift year to year, so confirm the current details before you register or run.
Every ultra distance at Stone Cat runs the same 12.5-mile loop through Willowdale State Forest. The 100K covers it five times, the 50M four, the marathon two plus two short 1K loops at the start, and the half marathon one plus a 1K loop.
The loop is constant rolling terrain rather than one big climb, a mix of double track and single track carrying about 1,100 feet of gain each time around. Held in early November, fallen leaves can hide roots and rocks that would otherwise be obvious, so respect the footing on loop one the same way you will need to on your last loop.
Stone Cat runs on real deadlines, not soft suggestions. The 50M field must start its final loop by 3:00 PM, and the 100K field by 4:00 PM, but the course itself shuts down for every distance at 7:00 PM, 14 hours after the 5:00 AM start. There are no race-day distance changes and no drop-downs, so if you are on the bubble, decide your entry distance well before race morning.
This is a cupless race: bring your own bottle, cup, or hydration vest, because aid stations will not have disposable cups, bowls, or utensils. Each 12.5-mile loop has one aid station at the start/finish and a second near the halfway point, stocked with hydration mix, bananas, dried fruit, cookies, chips, sandwiches, and boiled potatoes. The 10K course only has aid at the start/finish, so carry what you need if you are running that distance.
The 3:00 PM and 4:00 PM final-loop cutoffs are not the finish line, they are checkpoints that determine whether you get to keep running at all, so build your pacing around them explicitly.
Because the final-loop cutoff is a hard go/no-go gate, treat your first two or three loops as the place to build a real buffer, not just complete the miles. A grade-adjusted pace target for the rolling terrain gives you an honest number to hold, and holding it early is far easier than trying to make up time on tired legs during loop four or five.
The loop format hands you clean data every 12.5 miles: use it. After two or three loops, a finish-time projection built from your actual splits tells you honestly whether you are on pace to start your final loop before the cutoff, which is far more useful than trusting a flat-course estimate on rolling New England terrain with roots underfoot.
⏵ Free tools to pace this course
Two aid touches per loop is a predictable rhythm, but the cupless format means you need your own hydration system dialed in before race morning, not figured out on the trail.
Aim for roughly 60 to 90 grams of carbohydrate per hour, staged around the two aid points on each 12.5-mile loop. Boiled potatoes, quesadillas, and PB&J sandwiches at the aid stations add real food variety on a long day, but treat them as a supplement to a per-hour carbohydrate plan, not the plan itself.
Since this is a cupless race, carry a bottle, cup, or vest from the start, not just for the 10K but for every distance. Keep sodium in the 300 to 700 mg per liter range, and early November in coastal Massachusetts can run cool, so do not assume you need less fluid just because the temperature is dropping.
⏵ Build your fueling plan
Get a carb, sodium, fluid, and caffeine plan per hour built for your weight, your goal time, and a cool November day in the forest with the free ultra fueling calculator. Browse the rest of the free running tools at the tools hub.
⏵ Train for it with Summit Line
Get a race-day plan built around YOUR fitness, this exact repeated-loop cutoff structure, and your projected splits. Summit Line reads your real training, paces you against Stone Cat's hard 3:00 and 4:00 PM final-loop cutoffs, and rehearses your fueling so race day is something you execute, not guess at.
Stone Cat is a loop race, not a mountain race, and that shapes the difficulty. Every distance rides the same 12.5-mile loop through Willowdale State Forest, double track and single track with roots and rocks and about 1,100 feet of gain per loop. The 50M runs that loop four times, the 100K five, so total climbing lands in the 4,400 to 5,500 foot range. Held in November, fallen leaves can hide the footing late in the race, and it is a cupless event, so you carry your own hydration between the two aid points per loop. None of that is extreme on its own; the challenge is repetition and a genuinely hard course close.
The clock starts at 5:00 AM. To continue past your final loop, 50M runners must start it by 3:00 PM (37.5 miles covered in 10 hours), and 100K runners by 4:00 PM (50 miles in 11 hours). The course closes for everyone, regardless of distance, at 7:00 PM, 14 hours after the start. There are no race-day changes of distance and no drop-downs, so pick your entry distance with those cutoffs in mind, not on race morning.
With two aid points per 12.5-mile loop and a cupless format, plan to carry your own bottle, cup, or vest and refill on a predictable schedule rather than hoping for disposable cups. Aim for roughly 60 to 90 grams of carbohydrate per hour and sodium in the 300 to 700 mg per liter range, leaning higher if November weather runs mild and humid. Aid stations stock bananas, dried fruit, cookies, chips, PB&J, boiled potatoes, and quesadillas, useful variety but not a substitute for a per-hour plan you build ahead of time with the free ultra fueling calculator.
The repeated 12.5-mile loop is a genuine advantage for a first ultra: you pass the start/finish area every loop, so crew logistics, drop bags, and mental math stay simple. The terrain is rolling rather than mountainous, no single climb defines the day, but roots and rocks under November leaf cover mean footing takes real attention every loop, not just the last one. With a firm 3:00 PM final-loop cutoff for the 50M, go out conservatively on loop one so you are not racing the clock on loop four.
Willowdale is constant rolling terrain rather than flat or mountainous, a mix of double track and single track with a fair share of roots and rocks throughout. With the race held in early November, fallen leaves can obscure footing on top of the natural roots and rocks, so a conservative early pace protects you from a turned ankle as much as it protects your legs for the later loops.
Registration opens through trailanimals.com and the race has historically sold out, with no refunds, transfers, or deferrals except for documented emergencies. Because the 50M doubles as the 2026 RRCA Massachusetts State Championship, expect a competitive field at the front even though the club keeps entry costs low. Register as soon as the window opens if you want a spot.
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<a href="https://runsummitline.com/guides/tarc-stone-cat-trail-festival">The TARC Stone Cat Trail Festival course guide</a><iframe src="https://runsummitline.com/embed/race/tarc-stone-cat-trail-festival" style="width:100%;max-width:420px;height:180px;border:0;" loading="lazy" title="TARC Stone Cat Trail Festival course guide by Summit Line"></iframe>This guide is independent and for planning only. The course details, dates, cutoffs, and aid stations come from public sources and can change year to year, so confirm the current specifics with the official race before you register or run. The fueling and pacing advice is general and not medical advice.