Rock Ledges Research Articles

Ottawa University Natural Area

The Ottawa University Natural History Reservation, acquired in 1968, encompasses 30 acres of land on the south side of Middle Creek in the SW 1/, NW 1/4, Sec. 19, T. 18S, R. 19E, Franklin County, Kansas. The Reservation is accessible via county road from old U.S. 50 near Homewood. The Reservation has no roads, established trails, or facilities. The Reservation ecosystem is mature oak-hickory forest. Dominant tree species on upland slopes include shagbark hickory (Carya ovata), chestnut oak (Quercus muehlenbergii), white oak (0. alba), post oak (Q. stellata) and red elm (Ulmus rubra). Dominant trees in the riparian area of Middle Creek are hackberry (Celtis occidentalis), bur oak (Q. macrocarpa), and bitternut hickory (C. cordiformis). A total of 32 species of trees have been found at the Reservation, including 11 species of oaks known to occur in Kansas except Shumard's oak (Q. shumardii). Since the property was first deeded in 1865, no apparent major human disturbance, such as fire or clear cutting, has taken place. This view is supported by tree-ring samples which show some of the oaks of the Reservation are over 130 years old. The only change in community structure to occur during this century has been the loss of most American elms (U. americana) to Dutch Elm disease. The rock ledges along Middle Creek, which represent outcrops of the Tonganoxie Sandstone member of the Stranger Formation, contain extensive growths of ferns; thus the Reservation is often referred to as Ferndells. Common taxa include maidenhair ferns (Adiantum pedatum), Woodsia obtusa, and Polypodium sp. Associated with the ferns are mosses, lichens, and liverworts. On drier sites the understory consists of coralberry (Symphoricarpos orbiculatus) and wild gooseberry (Ribes missouriense). The rare puttyroot orchid (Aplectrum hyemale) is present at the base of rock ledges. Since the Reservation was acquired, the area has been used solely for field trips by biology classes from Ottawa University. Good inventories of trees and other woody plants, ferns and fern allies, wildflowers, and lichens have been made, and field studies have concentrated on plant community composition, soils, and leaf litter decomposition. Inventories of the fauna of the Reservation are incomplete. Although the larger mammals are well known (e.g., raccoon, opossum, and white-tailed deer), little is known of what species of small mammals, reptiles, amphibians, birds and invertebrates are present.

First North American Nesting and Occurrence of Haliaeetus albicilla on Attu Island, Alaska

The nearctic range of White-tailed Eagles (Haliaeetus albicilla) is listed as casual in the Aleutian Islands, Alaska (Attu, where probably breeds, Unalaska), in eastern Greenland and off Massachusetts, near Nantucket Lightship (AOU 1983). The species breeds only in western Greenland in the nearctic; a breeding report from Baffin Island has not been confirmed (AOU 1983). Reference in the AOU Check-list to H. albicilla breeding at Attu is based on data presented herein. We discovered an active aerie of this species on Attu Island (52049'N, 173010'E) in 1982. We have numerous observations of four individual H. albicilla there in May to September, 1977 to 1986 (summary follows). These observations and the nest site are all from the river valleys and coastline at the east end of Attu Island. We located the active nest in Temnac Valley on 25 May 1982 after watching both adult eagles take turns sitting in a rocky depression on a cliff ledge. On subsequent trips to this site in 1982 (31 May, 4 June) both adults were seen attending to a single downy chick. Photographs of the nest site are on file at the University of Alaska Museum (UAM). The same nest was active in 1983 with a single chick present. This chick was fledged and feeding on pink salmon (Oncorhynchus gorbuscha) with the adults along the Temnac River in September 1983. This nest has not been active since 1983; only one adult eagle has been recorded at Attu since 1983. The nest site was located on the north side of Temnac Valley, 2.7 km from the Temnac River mouth (and salt water) at approximately 80 m above sea level. The nest cup sat on a fractured rock ledge 20 m up the southeast face of a rock pinnacle. This pinnacle stood immediately in front of a south-facing 40-m high cliff face. A heavily vegetated 350 talus slope stretched from the pinnacle base to a point close to the river, roughly 30 m away. With a rim about 10 to 15 cm high on the outside, the nest was approximately 1 m in diameter. The wellpacked cup consisted of kelp (probably Laminaria), fronds and rachis of Athyriumfilix-femina, and Elymus arenarius. Stalks and a few umbel heads of Heracleum lanatum were included in the rim. This is a similar to contents from Aleutian nests of Bald Eagle H. leucocephalus (Murie 1959).

Experimental evaluations of substrate types as barriers to sea urchin (Strongylocentrotus spp.) movement

Descriptive evidence that sandy surfaces and rock ledges inhibit progress of grazing sea urchins prompted an experimental investigation of physical obstacles to urchin movement in a subtidal area of reef and kelp off southern California in 1980. In laboratory experiments, we found that both red (Strongylocentrotus franciscanus) and purple (S. purpuratus) urchins can negotiate sand using their oral spines, although purple urchins are slower and more hesitant to do so. In field experiments, we observed the fates of starved red urchins transported to replicate plots within stands of sand-or rock-based understory kelp (Pterygophora californica). Urchins in rock plots retreated to nearby crevices from where they ate attached kelp. After finding kelp blades, urchins soon disappeared from sand plots because individuals in small groups may have difficulty holding and eating attached kelps on unconsolidated surfaces. In another experiment, red and purple urchins reached kelp on a rock ledge by mounting an artificial ramp. We conclude that by using their tube feet, individuals of both species move best over flat, hard surfaces, although soft substrate may constitute a major barrier only to purple urchins. In the absence of effective predator control, urchins can surmount most sand or rock barriers when water motion subsides. Hence, their ability to coordinate spine movements to negotiate soft substrates may be an adaptation to invade kelp refuges during quiet periods if preferred drift food is unavailable.

The biology of Euryattus sp. indet., a web‐building jumping spider (Araneae, Salticidae) from Queensland: utilization of silk, predatory behaviour and intraspecific interactions

The biology of an aberrant saltioid spider, Euryattus Thorell sp. indet., is described from observations in a Queensland rain forest and the laboratory. Pronounced morphological and behavioural changes occur during post‐embryological development. Juveniles spin webs, but adult females make ‘suspension nests’ by suspending a curled‐up leaf by heavy guylines from a rock ledge or vegetation. Adult males spin neither webs nor suspension nests. Females oviposit inside their suspension nests, but if denied access to leaves for suspension, they spin and oviposit in webs similar to those spun by juveniles. The flat, papery egg sacs of Euryattus are atypical for a salticid, being more like the egg sacs of many of the Gnaphosidae. Intraspecific display behaviour has characteristics in common with typical salticids, but also includes unique features. Male courtship includes vibratory displays performed on the surface of the suspended leaf. Mating occurs inside the curled‐up leaf. Males co‐habit with sub‐adult females in suspension nests. Females take over suspension nests of other females and eat each other's eggs. Normal locomotion, intraspecific interactions, and predatory behaviour are characterized by frequent leaping. Euryattus routinely makes long and accurate leaps on to prey, including flying insects intercepted in mid‐air and spiders and insects located in alien webs. The phylogenetic implications of the unusual characteristics of Euryattus are considered.

Rippled Scour Depressions on the Inner Continental Shelf Off Central California

ABSTRACT Side-scan sonar records taken during the recent Coastal Ocean Dynamics Experiment (CODE) show elongate, shore-normal rippled depressions of low relief on the inner continental shelf off central California between Bodega Bay and Point Arena. These features extend up to 2 km from the coast into water depths of up to 65 m. The proposed mechanism for their generation is storm-generated bottom currents associated with coastal downwelling during the late fall and winter which scour the surficial fine-sand sediment and expose the coarser-sand substrate in the depressions. The zones of most intense erosion and the irregular spacing of the features may be controlled by submerged rock ledges and other prominent coastal features. The large straight-crested ripples within the depressions (heights to 40 cm; wavelengths to 1.7 m) are probably formed by large-amplitude, long-period surface waves generated by winter storms.

Nesting of Grey Heron (Ardea cinerea L.) on Sea Islands of South Primorye

The nesting of Grey Heron (Ardea cinerea L.) on rocks of sea islands of the Great Peter's Bay was observed periodically from 1969. There are the following three colonies, being numbered (in 1982) 630 pairs on Furugelm Island, 23 pairs on the of Gildebrandt Is. and 69 pairs on a small rock off Butakov Cape. The colony of Furugelm Is. increased in number approximately by 10 times from 1969 to 1982 most of all due to establishment of Marine State Reserve in 1980. Evidently, heronries on islands appeared not long ago, migrating here from the continental coast. This species arrives in south Primorye in middle March, egg laying in the insular colonies in the first half of April, chicks appear in the first half of May and nests are left in early July. Most nests are built just on rock ledges or on the ground; material for nests used (n=8) consists of Chenopodium sp. (57.8%) and Artemisia sp. (32.1%). An average number of eggs in clutch, was 3.4 (n=26) in 1972 and 3 (n=25) in 1979; number of fledglings (average) was 1.33 (n=15) in 1980. Behavior of chicks at the age of more than one month is characterized specific features connected with the terrestrial location of nests allowing to move lightly within the heronry in any direction. They taken away food in chicks from other broods (about 15 chicks gather around the bird with food); cases of kill of the youngest ones by oldest both in their own brood and from the others are common, aggressiveness of chicks increase in time of feeding; one case of cannibalism was observed when a fledgling ate two chicks from the neighbouring nest. A main reason of mortality is a slaughter of the youngest chicks by eldest; chicks from the late broods survive rarely being killed from trauma or hunger. Herons forage on the continent. A distance from colonies to feeding grounds ranges from 10 to 35km. Chicks are basically fed with the following fishes occurring in brackish and freshwater reservoirs: Carassius auratus, Phoxinus lagowskii, Leuciskus brandtii, Gasterosteus aculeatus, Hyporhamphus sajori and Gymnogobius macrognatus.

Scapania lingulataBuch in the British Isles

Scapania lingulata is reported from five vice-counties in Scotland and from one in Ireland, two gatherings bearing ♂ shoots and one with perianths. It differs from S. scandica in its larger gemmae, from S. praetervisa in its broadly rounded postical leaf lobes, and from both species in its larger leaf cells, more numerous oil bodies and polyploid chromosome complement. Usually it grows on base-deficient earthy banks but also on base-rich rock ledges.

Excavation of World’s Largest Underground Powerhouse

The LG-2 site is located in the nordic region of northwestern Quebec and is the principal installation of the La Grande River hydroelectric power development. As such, it presents formidable problems in organization, logistics, contract administration, and construction techniques. The powerhouse contains 16 generating units; each of 333 mw and required 3,650,000 cu yd (2,792,000 m³) of rock excavation. The rock is granitic gneiss typical of the Canadian shield region and is of exceptionally good quality. Rock support is entirely by rock bolts with shotcrete used locally. Roof arch deformation is minimal. Considerable specialized excavation equipment was used. Rock pillars at the intake and rock ledges to support the main overhead cranes in the powerhouse complex were successfully carved by controlled blasting. Economies in excavation were achieved by relying on field control by a geotechnical team rather than design conservation.

Holocene Cementation of Carbonate Sediments in the Florida Keys

ABSTRACT Previously undescribed examples of Holocene cementation of carbonate sediment have been discovered at two localities in the Florida Keys. Slabs of weakly cemented carbonate sand were discovered on a continuously submerged portion of White Bank, 3.1 km SE of the Mosquito Bank tower. The cement comprises furry coatings of acicular crystals interpreted as aragonite on basis of morphology, results of staining tests, and high-strontium, low-magnesium content. This is a normal form of submarine cement. Near the southeasternmost corner of Bahia Honda Key carbonate rock ledges crop out discontinuously along a 46 m foreshore stretch of sandy beach. Rock texture is like that of adjacent unconsolidated beach sands. Grains range from fine sand to free gravel, commonly in alternating layers within a single exposure, and most of the rock is laminated. The rock dips seaward, at approximately the same angle as the beach surface, but is apparently a form of cay rock. The rock is weakly cemented by rhombic crystals that by electron probe microanalysis were determined to have low strontium and relatively low magnesium content. This suggests that the cement is low-magnesium calcite. Similarly cemented carbonate sand occurs as much as one meter below the backshore surface, and at depths of 16 to 25 cm in a freshwater marsh lying inland from the beach. The relatively low magnesium content of the calcite and the salinity of water in contact with the rock suggest that cementation occurred in the zone of fresh water-sea water mixing.

Rock Bit Technology - The Effect On Drilling Costs

Introduction The development of rock bits has been an evolutionary process. Modern-day rock bit technology had its beginning in 1909 with the introduction of the first rotary-cone rock bit. Since that time, rock bits have been continually improved. These improvements were highlighted by the introduction of the tricone bit in 1933, jet bits in 1948, tungsten carbide insert bits in 1951, sealed bearings in 1960, shaped and extended tooth-shape inserts in 1967, and journal bearings in 1970. The net effect of the rock bit evolution has been increased performance and reduced drilling costs. By ncorporating special lubricants in specially sealed cones, bearing life has been extended by maintaining a well-lubricated bearing and preventing the intrusion of mud and abrasives in the bearing. The development of tougher tungsten carbide materials has resulted in extended tooth-shape insert designs closely paralleling steel tooth bit configurations. This has permitted the use of longer-life insert bits in the faster drilling intervals. The long-life tungsten carbide cutting structure with sealed-lubricated bearing systems (roller and journal) has greatly extended bit life. Runs exceeding 100 hours and/or several thousand feet are not unusual. First Rotary Rock Bit On August 10, 1909, Howard R. Hughes patented the first rotary rock bit, which he called a "boring drill".(1) Prior to this time, the use of the rotary drilling process had been limited to soft formations because harder formations were difficult or impossible to drill using the scraping action of the drag bit. The initial rolling cutter bit resembled two pipe reamers set on journal bearings attached to a drill pipe sub (Fig. 1). This enabled the rotary drilling process to drill formations which were too hard to drill using the scraping action of the drag bit. The early designs utilized cones which did not mesh. Consequently, the bit "balled up" in soft shale rathereadily. This, along with the slower penetration rates, kept the bit from gaining wide acceptance during the early years and the drag bit remained as the more popular tool for drilling the soft formations encountered on the Texas Gulf Coast. Self-Cleaning Cones As the rotary process of drilling spread inland from Texas Gulf Coast, new formation combinations were encountered which created a serious problem. Inter-bedded layers of plastic shale and hard rock ledges often necessitated many round trips to alternate the drag bit with the rock bit. A bit was needed to drill both the hard and soft formations.(2) In 1925, this problem was solved with the introduction of a two-cone hit with intermeshing teeth (Fig. 2). As the teeth of one cone passed through the grooves on the opposite cone, accumulated formation was pushed from the grooves of the opposing cone – thus the name self-cleaning. The new cutting structure enabled the drilling industry, for the first time, to make hole through both soft and hard formations with a single bit, thus markedly reducing over-all time of each well. Anti-Friction (Roller) Bearings Until 1932, the basic bearing of rolling cutter hit remained the journal type.

Lithological Control of High-Water Rock Ledges in the Vale of Glamorgan, Wales

Ledges at, or somewhat above high tide level have been the subject of considerable controversy regarding the question of whether such ledges provide evidence of a former higher sea level. In the macro- tidal, storm wave environment of the Vale of Glamorgan, ledges are related to lithological controls, contemporary storm wave activity and changes in sea level. In the Liassic outcrops, analysis of the detailed lithology demonstrates that the ledges occupy the most favourable lithological locations. Therefore such ledges cannot simply be correlated on the basis of height with the level of a former sea. The form of the ledges appears to provide both evidence of former sea levels at about 5 m and 1-2 m above its present level, and also significant indi- cations of the potency of contemporary storm wave activity. It is considered that both greater appreciation of the influence of lithology on ledge formation, and the recognition of high intensity, low frequency storm wave attack, must precede the utilization of high-water rock ledges for the reconstruction of former sea levels.

Tidal studies on Aldabra

The oceanic tide at Aldabra possesses a very large range for an atoll owing to the influence of the Mozambique Channel. The mean spring-tide range, expressed as 2 ( M 2 + S 2 ), is 2.74 m. This is much greater than the 0.5 m common to the majority of central Pacific atolls, and the 0.7 to 1.7 m for Indian Ocean atolls. Ten tide-recording stations were set up by members of the expedition. Foxboro—Yoxall tide-gauge records were obtained from most sites, though there are few accessible rock ledges near deep water suitable for the instrument, especially in the lagoon. Visual records were used extensively in a detailed study of the tidal system in Passe Houareau. Tidal predictions for Aldabra found in Admiralty Tide Tables possess marked lagoonal characteristics. They originate from ‘Grand Poste’, a site well within Grande Passe. It is recommended that records for Passe du Bois be taken as standard since they most closely represent the oceanic tide. Empirically derived tide-predicting graphs are presented for key stations around the atoll, using Kilindini as standard port. Reduction in tidal range is pronounced in the lagoon and is conspicuous even near the mouths of the major channels. Within Passe Houareau spring-tide amplitudes may be a mere 1.2 m only 500 m from the channel mouth where the oceanic range is 3.3 m. Time lag increases lagoonwards more rapidly at Passe Houareau than at either Passe du Bois or Grande Passe, and is greater at low water than at high because of the very shallow nature of the lagoon floor. The greatest recorded phase lag occurs at the head of Bras Cinq Cases, where high water is delayed by 4 1/4 h at major spring tides: at neaps the whole region is dry at high water. Harmonic analyses are presented for one oceanic and two lagoonal stations. Computer synthesis of neap tides in the lagoon demonstrates a monthly masking effect produced by prominent shallow water harmonics. This results in the lagoon being virtually tideless on the smallest neap tides. Strong higher harmonics are indicated by visual records for Ilot Marquoix at the eastern end of the lagoon. These are characterized by a plateau-like high water, where the level commonly remains stationary for over 3 h. Lagoon tide curves are markedly asymmetrical, and often show linear ebb profiles, indicating that the lagoon behaves as a simple water-filled basin in many areas. Drainage off lagoon platforms is slow, water level falling by only 3 to 5 cm h -1 . This results in the tide ebbing for to 10 h out of the 12 1/2 h cycle. Towards spring tides more water enters the lagoon through Passe Houareau than can drain away before the next tide. Water level gradually builds up until at major springs a foot of water covers the lagoon platform at low tide. Extreme low water coincides with neap tides. Because of this ponding effect significant differences in insolation are experienced by marine bottom communities. On oceanic platforms extreme low water coincides with spring tides and occurs at midday: in the lagoon, platforms are most exposed between 06h00 and 08h00 and are always covered at noon. The effects of solar insolation are therefore minimal throughout much of the Aldabra lagoon, but are at a maximum around the coast. Tidal currents were measured in each of the Passes. In the western channels maximum values of 1.5 m s -1 (3 knots) were recorded in Passe du Bois. In Passe Gionnet a peak ebb value of 3.7 m s -1 (7.2 knots) was attained at high springs, with 3 m s -1 (6 knots) sustained for over 2 h. Flow/ebb current reversals are rapid, and in Passe Gionnet accompanied by the development of standing waves. Many channels are floored with trains of reversing sand megaripples. Elsewhere scour is appreciable; a wire mesh shark cage on the floor of Passe du Bois being undercut by 25 cm in 2 weeks. Transitory megarippled sandbanks occur on the eastern flank of Passe Houareau, and bottom facies throughout the lagoon are sculptured by the strong tidal scour.

Lithological Control of High-Water Rock Ledges in the Vale of Glamorgan, Wales

Ledges at, or somewhat above high tide level have been the subject of considerable controversy regarding the question of whether such ledges provide evidence of a former higher sea level. In the macro- tidal, storm wave environment of the Vale of Glamorgan, ledges are related to lithological controls, contemporary storm wave activity and changes in sea level. In the Liassic outcrops, analysis of the detailed lithology demonstrates that the ledges occupy the most favourable lithological locations. Therefore such ledges cannot simply be correlated on the basis of height with the level of a former sea. The form of the ledges appears to provide both evidence of former sea levels at about 5 m and 1–2 m above its present level, and also significant indications of the potency of contemporary storm wave activity. It is considered that both greater appreciation of the influence of lithology on ledge formation, and the recognition of high intensity, low frequency storm wave attack, must precede the utilization of high-water rock ledges for the reconstruction of former sea levels.

A comparison of the insulative and reflective properties of the fur of desert kangaroos

1. 1. The reflectivity of the furs of two species of desert kangaroo to solar radiation was measured and the effect of season, site on body, and wind speed on their fur insulation was determined. 2. 2. The red kangaroo Megaleia rufa which lives on the exposed open plain has fur which gives greater protection from solar radiation in summer and from heat loss in winter than does that of the euro or hill kangaroo Macropus robustus, which shelters in caves and under rock ledges. 3. 3. The fur insulation of both the kangaroos is similar to that of tropical and temperate zone eutherian mammals, even though they have a much lower basal heat production than eutherians.

Contributions to the ecology of Colorado tick fever virus.

Studies were conducted in 3 different habitats in Mill Canyon, Ravalli County, in southwestern Montana on certain biological phenomena that affect the dispersal and maintenance of Colorado tick fever in its natural biocenose. During the study 399 small mammals were captured, in descending order of frequency: Peromyscus maniculatus, Citellus lateralis, Neotoma cinerea, Eutamias amoenus, Clethrionomys gapperi, Microtus longicaudus and Glaucomys sabrinus. Capture-recapture data did not prove amenable to statistical treatment, so comparisons of population levels were made by animals caught per-trap-night. Of the rodents collected, P. maniculatus proved most amenable to manipulation, and populations of this species were stable and uniformly distributed throughout the study area. Adult D. andersoni occurred primarily in alpine meadows; larvae mainly in rock ledges in the same area; nymphs for the most part did not respond to the CO2 technique. Adults and nymphs were active during May to July, while larvae were collected July and August. Infestation of rodents ranged from 16% in C. gapperi to 100% in C. lateralis. C. lateralis and N. cinerea were most often infested: average 7–12 ticks per capture. Ixodes ochotonae was also recorded in the study area. Virus was isolated 32 times from pools of D. andersoni nymphs and larvae off rodents but never from wild-caught unfed larvae. Positive pools ranged from 15% in 1964 to 35% in 1966. The greatest number of positive pools (20–53%) was taken from C. lateralis and N. cinerea. In 1964, 11 of 315 P. maniculatus blood samples, 3.5%, were positive for CTF virus; in 1966, 4 of 68 rodent blood samples, 5.9%, were positive. These latter isolations consisted of 2 samples from P. maniculatus and 2 from C. lateralis. The significance of the data gained in this study in the maintenance of CTF virus within the biocenose is discussed.

A Bioclimatological Comparison of the Summer Day Microenvironments of Two Species of Arid‐Zone Kangaroo

Two large kangaroos, the red kangaroo (Megaleia rufa) and the euro (Macropus robustus) live in the arid regions of Australia. On hot summer days they are found in entirely different microenvironments: red kangaroos in the shade of small desert trees in relatively open country and euros around rocky outcrops in caves and under rock ledges. Measurement of the temperature and radiation characteristics of these microhabitats showed that the euro avoided much of the heat load of the desert, particularly the radiation heat load. While the solar radiation influx reaching the red kangaroo resting site was only about 20% of that incident on open ground it still resulted in the radiation temperature of this microenvironment exceeding the animal's body temperature by as much as 30°C when air temperature also exceeded the body temperature. Considerable evaporative water loss would be expected under these circumstances. Radiation heat loss from the red kangaroo microenvironment to the sky, possible in the late afternoon, may be used by the animal to reduce the amount of water required for temperature regulation.

Additions to the Moss Flora of Arizona

Eleven species of mosses are reported for the first time from Arizona. The moss flora of Arizona includes 362 species (Haring, 1961) but exploration of geologically and climatically unique areas continues to produce new records. The 11 species listed below are from two unusual areas. Eight species grew in localities associated with the Mogollon Rim, in canyons dissecting the rim, at the base or top edge of the rim, and in a caldera near the edge of the rim. The Mogollon Rim is a precipitous escarpment about 200 miles long and, in the localities visited, is 488-610 m high. The vegetation on top of the rim, in Coconino County, is ponderosa pine forest. At the base of the rim, in Gila County, it is chaparral and pinyon-juniper woodland. Within the caldera, the water level of Stoneman Lake fluctuates greatly but the lake seldom goes completely dry. The other three species were found only in a spruce-fir forest in the White Mountains, Apache County. The collections cited are deposited in the Haring Bryophyte Herbarium at the Museum of Northern Arizona with one exception as noted. Claopodium pellucinerve (Mitt.) Best. COCONINO CO.: Side canyon off West Fork of Oak Creek Canyon, moist crevice in canyon wall, 2,020 m, Johnsen & Dunn 621. Dicranella varia (Hedw.) Schimp. COCoNINO Co.: Common in West Fork of Oak Creek Canyon, on sandstone, soil and litter in wet areas, 1,654-1,921 m, Johnsen 509, 864; Dunn 644. Grimmia torquata Hornsch. ex Grev. COCONINO CO.: West Fork of Oak Creek Canyon, on a moist Supai sandstone ledge, 1,654 m, Johnsen 583. Mnium punctatum Hedw. APACHE CO.: Mt. Baldy, White Mountains, on soil and humus in a seepage area, 2,912 m, Dybdahl R416. Orthotrichum cupulatum Brid. COCoNINO CO.: Sycamore Canyon, in cracks in rock, 1,441, Atkins 25; above the Mogollon Rim, on rock, 2,287 m, Sprugel 132. GILA CO.: Base of the Mogollon Rim, on a rock ledge, 1,677 m, Sprugel 386 (MICH). Orthotrichum pumilum Sw. COCONINO CO.: Stoneman Lake, on Quercus gambelii, 2,049 m, Johnsen 1426. Orthotrichum texanum Sull. cocoNINO cO.: West Fork of Oak Creek Canyon, on a rock ledge, 2,020 m, Dunn 626. Platydictya jungermannioides (Brid.) Crum. cocoNINO CO.: Common in West Fork of Oak Creek Canyon, on top of and in crevices of sandstone and limestone in moist or seepage areas, 1,654-2,020 m, Johnsen 1461; Dunn 408, 409, 622, 638, 659. Platydictya subtile (Hedw.) Crum. COCONINO CO.: West Fork of Oak Creek Canyon, on bark of Fraxinus pennsylvanica ssp. velutina and Gambel oak, 1,677 m, Johnsen 594, 598. Sphagnum squarrosum Sw. ex Crome. APACHE CO.: Smith's Cienega on Mt. Ord, White Mountains, on banks of streams and springs and in marshy areas, 2,988-3,034 m, Dybdahl R591, R602, R603, R611, R613, R615. Sphagnum subsecundum Nees. (referable to S. platyphyllum (Lindb. ex Braithw.) Sull.). APACHE CO.: Smith's Cienega on Mt. Ord, White Mountains, on marshy ground, 3,034 m, Dybdahl R616. LITERATURE CITED HARING, INEZ M. 1961. A checklist of the mosses of the state of Arizona. THE BRYOLOGIST 64: 222-240. 1 thank Dr. Howard A. Crum for the identification of the Sphagnum species, Mr. Dale H. Vitt for work on much of the Orthotrichum material, and Dr. Lewis E. Anderson for help on many specimens of Grimmia. 2 Museum of Northern Arizona, P.O. Box 1389, Flagstaff, Arizona 86001. This content downloaded from 157.55.39.132 on Thu, 15 Sep 2016 06:12:38 UTC All use subject to http://about.jstor.org/terms

Three Propaguliferous Pohlias from Michigan

Three rare Pohlias characteristically producing brood bodies in the leaf axils of sterile stems have been found in northern Michigan. Pohlia annotina var. loeskei has been reported previously from the state, P. bulbifera has recorded but once, and P. proligera has been collected several times but only in a few localities. A number of species of Pohlia bear axillary propagula at least occasionally, but in North America only four species and one variety produce brood bodies so regularly that they are most easily recognized by them. Of these, P. annotina var. loeskei has recently been discovered for the first time in northern Michigan, where P. bulbifera has already been collected once, and P. proligera has been collected in a few localities. Because all of these are rare and generally known even to seasoned collectors, it seems appropriate to summarize here our knowledge of their distribution in Michigan and elsewhere. Pohlia annotina (Hedw.) Lindb. var. loeskei Crum, Steere & Anderson [var. decipiens Loeske] is a small, yellowish or dark green, relatively dull moss with narrow leaves and very small, pale, elongate, slightly twisted propagula ending in leaf primordia resembling minute horns. The propagula are somewhat larger than the subglobose brood bodies of typical P. annotina and shorter and less twisted than the similarly vermicular ones of P. proligera. It grows on moist, sandy or silty soil of disturbed banks, especially along trails and at roadsides, and sometimes on the thin soil of rock ledges. We have seen specimens from northern Italy; the variety is presumably more widely distributed in Europe, in Fennoscandia, for example, where it is not uncommon, in some localities more frequent than the type (Nyholm, 1958). It occurs in North America on St. Paul Island in the Bering Sea, southeastern Alaska, British Columbia, Washington, Idaho, Georgia, Iowa, Maine, Michigan, New Brunswick, New Hampshire, New York, Ontario, Quebec, Tennessee, and Vermont. Neither the species nor the variety has been recorded previously from Michigan. During 1965 and 1966 we made four collections, all in northern Michigan: MICHIGAN. CHEBOYGAN CO.: Moist sand, 10 ft. from the water level, Vincent Lake, Munro Township, Miller 3386. ALGER CO.: Moist sand over sandstone near summit of cliff, Pictured Rocks, near Miner's Castle, Miller 2721. LUCE CO.: Moist soil of river bluff near trail, Upper Tahquamenon Falls, Miller 3543 (with P. proligera); Crum, 1966. Pohlia proligera (Limpr.) Lindb. ex Am. is readily recognized by its pale, glossygreen color and twisted, vermicular brood bodies crowded in the upper leaf axils. It is found on moist, usually sandy soil, especially in disturbed places such as roadcuts and sometimes also on rocky ledges, particularly of sandstone. It is a northern species ranging from Greenland to Alaska and southward to California, Colorado, the Great Lakes Area, and New York. We can confirm records from the following parts of temperate eastern North America: Manitoba, Michigan, Minnesota, Nova Scotia, New 1 Herbarium, University of Michigan, Ann Arbor, Michigan. 2 Department of Botany, Michigan State University, East Lansing, Michigan. This content downloaded from 157.55.39.25 on Sun, 04 Dec 2016 04:52:25 UTC All use subject to http://about.jstor.org/terms 19671 CRUM & MILLER: PROPAGULIFEROUS POHLIAS 119 York, Ontario, and Quebec. Andrews (1935) reported it in Wisconsin as well. We have seen numerous specimens from northern and central Europe (south to northern Italy). According to Nyholm (1958) it also occurs in northern Asia, Madeira, and the Azores. It has been found in four counties in the Upper Peninsula of Michigan. The following records have been confirmed: MICHIGAN. ALGER CO.: Pictured Rocks, Steere; Nichols. Au Train Bay, Sharp. Scott Falls, Hermann. KEWEENAW CO.: Copper Harbor, Steere. LUCE CO.: Upper Tahquamenon Falls, Crum; Miller; Crum & Miller. MACKINAC CO.: Cut River ravine, Crum & Miller. Records from Luce and Mackinac Counties are reported here for the first time. Pohlia bulbifera (Warnst.) Warnst. is characterized by its dark or yellow-green, glossy color and pale, yellowish, globose brood bodies borne separately or in groups of two or three in leaf axils nearly all along the stems. It grows on damp, often sandy soil, on roadbanks and often at the margins of lakes, ponds, and rivers. We have seen specimens from Greenland, Alaska, northern Manitoba, Maine, Massachusetts, Michigan, New Hampshire, Nova Scotia, New York, Ontario, and Quebec. According to Nyholm (1958), it also occurs throughout northern and central Europe, northern Asia, and the Azores, but we can confirm its occurrence only in Finland, Sweden, Germany, and Poland. We have seen the specimen which Griffin (1962) reported from Whitefish Point in northern Michigan. It is correctly named, but it should be pointed out that the locality is in Chippewa and Luce County, as Griffin and later Darlington (1964) said.

Salt Weathering and Inselbergs

RECENTLY, Wellman and Wilson1 have directed attention to ‘salt weathering’, that is, ‘the fragmentation of rocks by the crystallization of salts’, as a geomorphic process of appreciable efficiency, especially in arid regions and along the sea coasts, but also at other places. They have shown that the formation of ‘rock meal’ and the development of pitted and cavernous rock surfaces are the most obvious symptoms of this type of rock decay. During my field work, particularly in the Alps of Central Switzerland, I have here and there come across rock meal linings as described by these authors, for example, under overhanging rock ledges and at cave entrances, and in some cases the presence of ‘salts’ was obvious, either visible in form of efflorescences or verifiable by the taste of the rock meal. Once, I could even watch a mouse licking eagerly the salty rock meal. Such observations certainly lend support to the authors' findings.

Probable tertiary sediments from a submarine canyon off Nova Scotia

Partly indurated sediment samples collected from a submarine canyon off Nova Scotia lithologically resemble rock units which occur on Georges Bank. Microfauna from some of the samples suggest a Tertiary age for the sediments. Topographic configurations along the canyon walls indicate that resistant rock ledges may occur there.