FIELD TRIP LEADERS
BOB HOWARD, FRANK HANNA, AND GEORGE DUNNE
Photographed and compiled by GENE FRITSCHE
George Dunne describes the origin of Cantil Valley, which is northeast of Mojave and in the mid-ground portion of the picture. The valley is a pull-apart feature formed between two offset strands of the Garlock fault. The northern strand that ends southwestward is near the highway where the vehicle is parked. The southern strand that ends northeastward is in front of the Rand Mountains in the background part of the picture.
We stopped to pick up a fast-food dinner in Ridgecrest, zipped through Trona, and set up our first night's camp by the light of a nearly full moon in an old limestone quarry at the north end of the Slate Range. Camp facilities were zero and a cold wind was howling through the camp. We could see the bright lights of Trona and the wind was favorable for the elimination of the well documented Trona odors. Shown is an early morning picture of our "Trona Heights" camp.
As we entered the Panamint Valley, we stopped for an overview of the geology. George Dunne first explained the extensional, half-graben origin of the valley. We could see fairly recent fault scarps and ancient shorelines along the front of the Panamint Range, which is in the right background. In this picture, Bob Howard is describing how the Panamint Valley was alternately filled to form a lake during the Pleistocene glacial periods and drained to form a playa during interglacial stages.
Bob Howard is describing for us the two major types of playas. The surface of the one we are standing on at the south end of Panamint Valley is soft because the water table is near the surface. This type of playa can easily trap the unsuspecting adventurer who ventures out on it. The recently uplifted front of the Panamint Range is on the right, with one of its alluvial fans creeping out onto the playa surface. The Argus Range is in the background.
This picture is looking north, just east of Panamint Springs, in the Panamint Valley. The Argus Range is to the left. Seen in the cutbank by the highway is the large-scale cross bedding of a fan-delta that advanced from left to right out of the Argus Range into one of the Pleistocene lakes that occupied the Panamint Valley.
Here the group is standing on the hard, clay surface of the playa at the north end of Panamint Valley. The surface is hard because the water table is much deeper than it was at the south end of the valley. The uniformly colored rocks in the left background belong to the Hunter Mountain batholith at the north end of the Panamint Range. The bedded rocks in the right background are the Cambrian through Pennsylvanian sedimentary rocks in the Panamint Butte area. The dark rocks near the top of the Panamint Range are Tertiary basalt flows that had their source to the west (left) in the Argus Range. These basalt flows supply evidence for the amount and direction of extension that occurred during the development of the Panamint Valley.
After crossing the Panamint Range, our first stop in Death Valley was in Mosaic Canyon, where the alluvial fan is composed of angular blocks of Precambrian Noonday Dolomite. Rapid uplift of the mountain range since deposition of much of the fan material has caused the stream in Mosaic Canyon to cut clear through the well cemented fan deposit to its base, exposing the unconformity between the fan and the Noonday Dolomite. The picturesque mosaic of cemented, angular blocks of orange dolomite in the basal fan deposits give the canyon its name. In this picture, the group is returning to the cars from our walk up the canyon. Death Valley and the Amargosa Range are in the background.
As in Panamint Valley, a lake also existed in Death Valley during the Pleistocene glacial periods. This lake has been named Lake Manly. Here our group of explorers stands on a pebble beach ridge in Death Valley that formed on a spit that was deposited with an east-west orientation out into Lake Manly. A clue to the fact that this was indeed a beach, is the presence of abundant, flat, rounded, skipping-type pebbles.
Our second night was spent in Death Valley in Texas Springs campground. The wind had died down, the temperature had gone up a bit, and we arrived in time to set up camp in the daylight. Here we are preparing a wonderful burrito dinner as the sun sets. After dinner, the old folks sat around a comfy fire and reminisced, while the youngsters disappeared to a nearby watering hole.