Search and Rescue Report

June, 2007
SW Oregon - Cretaceous Hornbrook Formation
By Michael Santino

My exploratory fossil trip into south central Oregon and north central California was more of a geology trip examining formations of late Cretaceous marine deposits. You would be amazed at the variety of ways sand, silt and mud can form sea floor, beaches and everything in between. The entire sequence is believed to be an Island arc chain accreted into the coast in late cretaceous times. This created conditions ranging from storm swept beaches to low energy deep and shallow bays over time.

I got a late start due to business I had to complete prior to starting the trip. I had to skip all the Jurassic exposures I wanted to explore but found two early Cretaceous outcrops in Days Creek in the area of the same name and Cow Creek in Riddle Oregon. Cow creek has some potential for an exploratory drift, no later than summer. Found a good drop off point up river and have at least one pickup point in downtown Riddle. The formation extends all the way to the Umpqua River with a possible pickup in Days Creek or Myrtle Creek. Potential exposure at the lumber company plant, riddle exit I5 south, about a mile from the freeway on the way to Riddle

The best find of the entire trip was is the most northerly exposure of the Hornbrook formation on Grave Creek road east of SunnyValley. It turns out this is BLM land with suitable locations for overnight camping. This part of the formation is dated the earliest part of the Hornbook formation at Middle Albian (112 to 99 mya). Some of this exposure overlaps the latest Albian exposure in Mitchell, Oregon. Five stops off one road of this exposure and I found fossils in four of the locations. Primarily mollusks (clams, trigonias and snails) Preservation is poor compared to Mitchell. But when I found fossils, I found a lot of them. I found one ammonite, possibly Allocrioceras, in matrix that fell from road cuts. There are at least two other major BLM roads through the area with potential for a large variety of fossils.

The following three days were spent exploring the area from Jacksonville, Medford, Talent, Phoenix and Ashland. Most of the Northern Valley is covered by new million dollar homes on five acre lots, vineyards and Orchards. I got onto one 100-year farm with a hill in the center on a fluke. As I was driving by, one of the owners was leaving the farm. I got permission for 10 minutes until her brother rescinded the permission due to fire hazard. The next lot I passed had their address engraved on a 5 foot slab of the Hornbrook sandstone.

I spent a day exploring accessible Bear Creek exposures in Ashland. The creek bed is non fossil bearing sandstone (Rocky Gulch Sandstone Member of the Hornbrook formation) From my explorations, the entire town of Ashland covers the best fossil bearing member of the Hornbrook, the Blue Gulch mudstone member. The only raw exposure of this member was at the intersection of the Railroad and Highway 99, which is the main street through town. I found about a dozen concretions in a twenty yard stretch in 3 different horizons. The concretions were hard mudstone, very good preservation for fragments of shells. The only other time I found this raw exposure of this member was in the town of HornBrook in Northern California in a creek bed at the south end of town on private property. I found an eroded exposure next to a new housing development at the Northern end of Ashland. A two foot deep trench showed extremely rich (black) soil with no trace of fossils. This also explains why an Ashland rockhound found an ammonite in town on the roadside.

The following day I spend exploring the area of Hilt, Hornbrook and Yreka. I visited at least 2 dozen exposures in these towns, surrounding areas and next to the freeway and the only fossils I could find were mortality layers right next to the freeway composed primarily of clams. At least 5 beds in one sequence with poor preservation, but access was the best of everything in the Hornbrook Formation. I5 south, one mile south of Hornbrook in the middle of the hill up the grade that goes back down into the Klamath river basin. This is probably ditch creek siltstone member of the Hornbrook formation.

Finally, I came to the part of the trip where I had specific instructions to public land with know ammonites. This exposure is in the Ishi wilderness area over fifty miles east out of Redding. A two hour trip in on some decent dirt roads. The best was a 1500 foot 1 one lane boulder strewn cliff hanger for 3 miles and only 2 turnouts. At the time, I was glad not to run into anybody else. I camped in the only public camp I've been in I didn't have to pay for. It had fire pits, tables and a toilet. It's nestled next to the lovely clear water Mill creek with slow moving water. It's pretty cold still at the end of June. I had the place to myself.

I got p at 5:30 AM, packed for a full day due to a 2 ½ mile hike to the dig site and started hiking by 7:00 AM. I made it about two miles, after traversing the trail through a gated ranchers property (the trail had it's own gates through the property). I could see the exposure in the canyon. It looked like a fresh slide had exposed at least 60 feet vertical and I could not see the bottom. The green color of the clay was oddly out of place in the forest-covered canyon but I could imagine it's dried out color matching that of the concretions from Gable Creek. I couldn't wait to start collecting. I got to the end of the ranch, turned a corner and ran into 3 mountain lions eating some thing; I hope it wasn't the rancher. My dog, Jenna, could not believe it and just stood there with her jaw on the ground. It was all I could do to keep from soiling myself. Two of the cats split quickly. The first though I had was of Jurassic park and the raptor hunting parties. The third cat just starred at me and growled. I am pretty sure it was a mother with 2 year olds. Moving forward could be interpreted as attempting to steal their food or harm the "kittens" (they definitely weighed more than I do) I decided my dog and I (with pick in hand) might be able to keep two of the cats busy, but not three. The day before, I watched a ferret drag off the freshly killed carcass of a squirrel and I figured the big mountain lion would have no problem with my ass. I hiked back, tried to notify the rancher, nobody was home. I found a road cut on the other side of the ranchers land that was lightly fossil bearing, grabbed some samples, hiked back, packed up and skedadled. I won't return unless I have company with guns. I left a note on the gate to fish and game land twenty miles from the site. I tried to get the number for local officials in Redding and was informed that unless the cats were walking through town, nobody would do anything.

The remainder of the trip, I explored exposures in the great valley sequence of California, in creek beds and road cuts west of Red Bluff, Cottonwood and Redding. The formation is exposed almost everywhere 25 miles west of Red Bluff. I asked permission from a landowner for an especially long stretch of creek and was rewarded with finding my first Belemnite in matrix and many more clams in multiple mortality layers. The sand preservation was better out of the creek bed, but still not good enough, or with enough variety to make it worthwhile for a return trip.

Trip Pictures