This is a really shady place in the trees below Mallory Cave. It has good sport/TR routes here on hueco-like sandstone.

This is a enjoyable small Flatiron with a decent amount of variety. It is routes from 5.5 to 5.11d, trad & sport, slab to overhanging, 1-3 pitches, sun and shade. It has even become one of the trial rocks for the reintroduction of limited, new fixed hardware (requires an application process and approval by FCC) for the Flatrions. It lies very close to the Mallory Cave Trail. However, it does apparently host a species of bats which close some of its routes each year.

From the 2006 Boulder Mountain Parks Website: For the protection of roosting Fringed Myotis Bats, the following area will be CLOSED to all users from APRIL 1st to SEPTEMBER 1st:

THE EAST FACE OF DER ZERKLE including the following routes: Sunnyside One, East Face Left, East Face Right. All other climbing areas on Der Zerkle and Mallory Cave Trail remains open.

Take Broadway to Table Mesa and turn W. on Table Mesa. Follow Table Mesa all the way to NCAR and park at the NCAR lot. Now take the "NCAR Trail" along the nature walk along the rim of the hill. Look for a trail that cuts left and down the hill to some switchbacks. Follow this trail all the way to the water tower and continue left of the tower down to the Mesa Trail. Look for the 3 fingered Flatiron with a diagonalling slash across its East Face. Here, you will come to a junction with a Boulder Mountain Parks info/map board. Take the Mallory Cave Trail up the hill for a nice hike. You will see several signs for climbing access, but stay on this trail. When you come to the junction of the climbing access to Dinosaur Mountain, take a right up the hill, which is still the Mallory cave trail. Keep following the trail until you see a sign for climbing access to "Der Zerkle." You'll see the nice cliffs just up the hill. :)