Thacher will offer a unique experience for Northeastern climbers as the only limestone cliff in the region. Europe and the American West have plenty of limestone climbing areas but this will be the only sizeable limestone sport climbing in the Northeast US. The area will provide plenty of challenging climbs on smooth crimpy faces and steep cave formations. Rock texture ranges from smooth to rough textured pocketed areas.


Thacher’s rock tells a tail of ancient seas filled with life. The eurypterid was a fearsome sea scorpion, sometimes bigger than a human (470-248 Million years ago).

Science: There are two layers of limestone at Thacher: the Manlius and the Coeymans. Like limestone in many western climbing areas the rock is filled with fossils including crinoids, trilobites, brachiopods and the fascinating giant sea scorpion. Thacher’s rock was important in the history of geological studies and was featured in textbooks since the 1800s.

The limestone at Thacher begins with the Manlius limestone and the beginning of the Devonian era. As you climb higher you will see the rock grow richer with fossils. The richest rock of all for fossils is the Becraft Limestone. This layer is not part of the main cliffs and is found at higher elevations in the park. Despite this you can still expect yourself to be crimping on crinoids on most routes.

Sport Climbing: “Sport” Climbing refers to climbing in which expansion bolts are used as anchors. Sport climbing is more suitable than trad climbing on softer rocks. In sport climbing the climber hikes into the bottom and climbs up to a top anchor. The belayer will lower the climber down. At Thacher rappelling and topping out will not be permitted. Climbers will walk up and out using a trail at the end of the day. There will be no legal access from the valley floor as that area is privately owned.


Thacher’s rock will cater best to more advanced climbers as the routes involve smooth slabs and bold overhanging bulges. Most beginners will find themselves climbing Thacher’s crack systems. Coeymans Limestone forms a strong cap rock and ranges from very smooth to, to worn and chossy, to beautifully textured. The majority of climbs will be on the Coeymans layer. Climbing on the Coeymans is a joy because it commands an excellent view and has a cool textured feel.

Features: Thacher’s rock has a few distinct shapes and features. Certain areas resemble giant onions with rounded shapes featuring hard bulge climbs on the bottom half. There are also plenty of smooth hard walls to climb. Most of these smooth lines will average 5.10+. For beginners there are just a few low angle slabs and mostly cracks. The crack sizes on average are perfect for the human hand and fingers. There are many aretes at Thacher which feel incredible as you are 600 feet above the Hudson valley so you will feel the exposure. Most climbs at Thacher will be short 35-50′ and some (usually harder lines) will be tall (70-100′).

People have been climbing Thacher’s cliffs since the Mahican Indians established hunting grounds on the lands above the cliffs. Read more on the climbing history here.

Check out our photo gallery below of the rock at Thacher:

Thacher’s Ice

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