Tony Grove Geology, 8 August 2021

13 hikers embarked from the Smith’s parking lot at 8:10 a.m. and began our hike at the Tony Grove backcountry parking lot by 9:00 a.m. The group’s goal was to visit 7 geological features in the Tony Grove back-country.  After passing through the campground we arrived at the south end of Tony Grove Lake and began a short, but steep climb to the cliffs above the west side of the lake.

Our first destination was “Polygamy Cave”.  We arrived at the cave at 10:14 a.m. with temperatures around 80ºF.  Skies were blue straight above us, but hazy off to the horizons due to the smoke from fires in California.  Some hikers decided to venture into the cave, while others explored outside.  During exploration, the “Extra Wives” cave was located.

After accounting for all hikers, the group left the somewhat established trails leading to the first cave and began 2.5 miles of back-country trekking.  While heading towards our next waypoint, “Teacup Cave”, the group actually stumbled upon a cave (name currently unknown) which wasn’t originally on the group’s itinerary.  We spent a few minutes at this cave, and then at “Teacup Cave” before a longer ramble through sinks and meadows to our next destination – “Snowcone Cave”.

There was still snow at the entrance of the aptly-named cave, but the amount of snow had diminished greatly from only 3 weeks earlier.  The group split at this point with some deciding to take a lunch break near “Snowcone Cave”, while others made the strenuous climb to “Main Drain Cave”.  “Main Drain” is the deepest cave in Utah with a depth of 1,227 feet.  It is also the 4th longest cave with just over 2 miles of the cave being mapped.  This splinter group relished in the feat of finding the cave and then joined the rest for a leisurely lunch at 1:00 pm with a cooler temperature of 70.

After lunch we took aim at locating “Double Sink Cave”.  Having hiked for about 3.7 miles from the start, we arrived at 1:50 p.m. at a sink just south of “Double Sink Cave” which appears to be home to two large owls, as this is the second time these owls have been seen in the area this summer.  Unfortunately the owls were flushed from their perches before any in the group could get a good picture.  After visiting “Double Sink Cave” we set off for our last target, “GMZ Cave”.

With “GMZ” under our belts, we head back to the Tony Grove back-country lot by way of the Naomi Peak trail, passing by the final geological point of interest on the groups itinerary – The Quartzite Staircase.  We made it back to the back-country lot at 3:05 p.m. and were back to Smith’s at 3:50 p.m.

Trip Summary:
  • Participants: David (leader), Dave W., Jane, Dave P., Ralph, Laurel, Susan, Brent, Ophelia, Ludger, April, Jack, Young
  • Drove 29 miles to the Tony Grove Backcountry Trailhead
  • Started hiking by 9:00, lunch about 12:50 to 1:20, back at the trailhead about 3:00 and Logan by 4:00
  • Slightly smoky skies (from distant wildfires), warm temperatures and mostly calm winds
  • Hiked about 6 miles with about 1400 feet of ascent and descent
  • Sites visited:  Polygamy Cave, Extra Wives Cave (not on the original itinerary), Unknown Cave (not on the original itinerary), Teacup Cave, Snowcone Cave, Main Drain Cave, Double Sink Cave, GMZ Cave

Thanks to David for the narrative and photos and video, and Dave P. and Dave W. for photos.

Looking to the north over Tony Grove Lake
Hiking up a path above Tony Grove Lake
Hiking though a meadow above Tony Grove Lake
All 13 hikers
Polygamy Cave
Unknown Cave
Teacup Cave
Snowcone cave
Double SInk Main Drain
Double Sink Cave
Main Drain Cave
GMZ Cave
Stromatolite fossils
Fossils Stairs
Coral fossils
Quartzite "stairs" north of Tony Grove Lake
Tree Hugging
Tree hugging
More tree hugging
Wild Fuchsia or Fire Chalice (Epilobium canum)
Stumped hikers?

Ferns at Polygamy Cave entrance
Hike video