Boulder Narrows rock (Leighty)
Mile 18.6 - In 1957, during a flow of 122,000 cfs, the top of this boulder was entirely submerged (Martin and Whitis, 2004). The driftwood was deposited during the same 1957 flood event (before construction of the Glen Canyon Dam in 1963).

Nature talk on a North Canyon walk (Leighty)
Mile 20.5 - Ron guides a discussion about flora and fauna along the trail in North Canyon.

Sacred datura (Leighty)
Mile 20.5 - Blooming along the trail in North Canyon, this sacred datura was a topic of Ron's discussion.

Sacred datura (Leighty)
Mile 20.5 - More blooming daturas.

Esplanade cliff (Leighty)
Mile 20.5 - Resistant, cliff-forming Esplanade Sandstone looms over much of this part of Marble Canyon.

Esplanade wall (Leighty)
Mile 20.5 - Hikers making the 1/2 mile trek toward the narrows formed by resistant sandstones of the Supai Group.

U-shaped narrows (Leighty)
Mile 20.5 - The curving joints are due to exfoliation of the fine-grained Esplanade Sandstone during the cutting of this slot canyon. Clarissa for scale.

Narrows pool (Leighty)
Mile 20.5 - The pool in the North Canyon narrows. Dan for scale.

Esplanade jointing (Leighty)
Mile 20.5 - Well developed curved jointing in the Esplanade Sandstone. John T. provides scale. See PANORAMA.

Uno chuckwalla (Leighty)
Mile 20.5 - The not-so-shy chuckwalla (Sauromalus obesus).

Dos chuckwallas (Leighty)
Mile 20.5 - Boy and girl chuckwallas?

Chuckwalla watchers (Leighty)
Mile 20.5 - Paul, Ron, Ana, and others stop to ponder the mysteries of chuckwalla life in North Canyon.

One of the Roaring Twenties (Leighty)
Mile 23.0 - One of the several rapids that make up the Roaring Twenties, 23-Mile Rapid (a.k.a. Indian Dick Rapid; {5}; 5' drop). The Redwall Limestone appears along the river here, although it is mostly covered. The Surprise Canyon Formation occurs above the Redwall just downstream of these rapids. Both rock formations are Mississippian in age (359 to 318 Ma).

Suggestive Supai spire (Leighty)
Mile 23.0 - 'Nuff said.

Fence fault (Leighty)
Mile 30.3 - This high-angle normal fault displaces the downstream side about 210 feet. Note the Redwall cliff on the right and younger, down-dropped Supai Group rocks on the left. Several small springs may be seen on river left at low water levels.

Redwall cliff (Leighty)
Mile 31.8 - The Redwall Limestone consists of four members and is up to 500 feet thick in Marble Canyon. It is Early to Middle Mississippian in age (350 to 337 Ma), significantly older than the overlying Middle Pennsylvanian bottom of the Supai Group. This range of time spanning the Late Mississippian and Early Pennsylvanian likely witnessed uplift and erosion. The contact between these units represents this period, and is termed an unconformity (specifically, a disconformity).

Stanton's Cave (Leighty)
Mile 31.8 - Stanton's Cave is about 150 feet above the river on the right. John's boat to the left. Robert Brewster Stanton was chief engineer of a railroad expedition that made the second run of the river in 1889 and 1890.

Stanton's Cave (Leighty)
Mile 31.8 - A bat gate was built in 1997 and allows bats to pass, but not people. The cave has several hundred feet of passages.

Redwall thunder (Leighty)
Mile 31.8 - The Thunder Springs Member of the Redwall Limestone across from Vasey's Paradise. This unit is Early to Middle Mississippian in age (~345 Ma).

Vasey's Paradise (Leighty)
Mile 31.9 - The springs emerging from the Thunder Springs Member support maidenhair, watercress, redbud, Apache plume, paintbrush, etc. Although not common in the Canyon, poison ivy grows here and at Deer Creek. George W. Vasey was a botanist who served with Powell. See PANORAMA. and VIDEO.

Vasey's spring (Leighty)
Mile 31.9 - Discharge is continuous, though seasonal, and is fed by groundwater originating at the Kaibab Plateau. Discharge rates have varied from 1 to 10 cfs (cubic feet per second). 10 cfs is 4,490 gallons per minute or 6.4 million gallons per day! See VIDEO.

Redwall Cavern (Leighty)
Mile 32.8 - This large cavern is located at a bend in the river about a mile downstream from Vasey's Paradise.

Redwall Cavern (Leighty)
Mile 33.0 - The cavern is carved into the Thunder Springs Member of the Redwall Limestone. The cavern is deceptively large. Thousands of people could find shelter here, but maybe not the 50,000 that Powell estimated.

Redwall spring (Leighty)
Mile 34.2 - A small spring issues from the lowest member of the Redwall Limestone (the Whitmore Wash Member). See VIDEO.

Nautiloid Canyon (Leighty)
Mile 34.8 - Lower Nautiloid Canyon is cut into the Whitmore Wash and Thunder Springs Members of the Redwall Limestone. The Whitmore Wash Member is Early Mississippian in age (~350 Ma).

Climb up into Nautiloid (Leighty)
Mile 34.8 - Boldly chasing after orthocone nautiloid fossils. What's 75 feet of broken limestone cliff? No problem! See VIDEO.

Nautiloid fossil (Leighty)
Mile 34.8 - This fossil is a type of cephalopod mollusk, specifically a straight nautiloid or orthocone. The largest of these nautiloid fossils is almost 1 meter in length. Bring water, as these ancient critters show best when wet.

Nautiloid fossil (close-up) (Leighty)
Mile 34.8 - Close-up of internal septa (chambered sections). Sharing the Early Mississippian oceans with primitive sharks, these squid-looking creatures were probably predators. Orthoconic nautiloids have been extinct since the early Mesozoic Era.

Nautiloid narrows (Leighty)
Mile 34.8 - View up Nautiloid Canyon. The fossil layer is in the Whitmore Wash Member of the Redwall Limestone, whereas the Thunder Springs Member forms the cliffs. See PANORAMA.

Redwall bedding (Leighty)
Mile 34.8 - The ol' polecat waxing poetic in the shade of Nautiloid Canyon. A canyon wren (Catherpes mexicanus) was also quite vocal here. Note the bedding in the Whitmore Wash Member.

Calcite crystals (Leighty)
Mile 34.8 - Large calcite crystals growing in a Redwall opening across from Nautiloid Canyon. These crystals were formed as carbonate-rich groundwater moved through the Redwall Limestone and precipitated calcite in the small opening. The opening is roughly a meter wide.

Caves and Arch of Sighs (Leighty)
Mile 35.8 - More solution features in the Whitmore Wash Member of the Redwall Limestone. Like elsewhere in the Redwall, the caverns form as groundwater slowly dissolves the carbonate rock. Groundwater in this area flowed along numerous fractures that are part of the 36-Mile joint system (Billingsley and Elston). The natural arch on the right is about 150 feet above the river.

Arch of Sighs (Leighty)
Mile 35.8 - Close-up of the arch in the Redwall ravine, referred to as the Arch of Sighs. This feature can also be termed a "bridge" as flowing water was a major agent in the formation of the opening.

Late afternoon float (Leighty)
Mile 36.5 - View W showcasing the entire geologic section observed since Lees Ferry. The Kaibab Formation caps the section and Cambrian carbonate rocks are present at river level. John's boat and some other rafts are downstream.

Temple Butte channel (Leighty)
Mile 39 - One of several exposures of the Temple Butte Limestone in Marble Canyon. In the eastern Grand Canyon, this Middle to Late Devonian (385 to 375 Ma) carbonate unit typically fills channels cut into the older Cambrian carbonate rocks. It is overlain by the Mississippian Redwall Limestone. Thus, there is a significant age difference between the Temple Butte and the rocks below (~100 Ma older) and above (at least 25 Ma younger).

Proposed dam site (Leighty)
Mile 39.5 - These Redwall narrows were a proposed site for the never-built Marble Canyon Dam. The Redwall Limestone so impressed Powell that he named this part of the river Marble Canyon.

Buck Farm Canyon (Leighty)
Mile 40.9 - View west into Buck Farm Canyon. A hiking trail follows this is relatively short canyon (about 3 miles) to the Marble Canyon, roughly 2900 feet above the river. The mouth of the canyon cuts through Cambrian carbonate rocks. The first mesquite trees along the river appear here (Ron Hill, pers. comm.).

Royal Arches (Leighty)
Mile 41.5 - An alcove in the Redwall Limestone, which really isn't an arch at all. Groundwater emerges from numerous small seeps.

Anasazi footbridge (Leighty)
Mile 43.1 - These logs perched above a ravine high in the Muav Limestone/Unclassified Dolomite likely represent a canyon trail used by ancient Canyon-dwellers.

Unloading at Eminence camp (Leighty)
Mile 44.2 - Everyone helping to unload the boats at Eminence camp near President Harding Rapid ({4}; 4' drop).

Eminence Fault (Leighty)
Mile 44.2 - The Eminence fault zone crosses through the Eminence camp area. This NNE-trending high-angle fault cuts diagonally throught the cliff from bottom left to upper right (at the notch in the cliff). There is roughly 200 feet of cumulative down-to-the-west displacement on this and other faults just east of camp.

View downstream from Eminence camp (Leighty)
Mile 44.2 - View downstream from Eminence camp. The upper part of the cliffs are Redwall Limestone, whereas the lower part is Cambrian unclassified dolomite and Muav Limestone. Several high-angle faults cut through this area. See SKETCH.