Clay Patches Research Articles

Integrated petrophysical and petrographical studies for characterization of reservoirs: a case study of Muglad Basin, North Sudan

Petrography, scanning electron microscopy, X-ray diffraction, and both conventional and special core analyses are applied to precisely reservoir characterize the Lower Cretaceous Bentiu and Abu Gabra Formations of the Muglad Basin, which is among the largest hydrocarbon reservoirs in South Kordofan, SW North Sudan. Based on this integrated study, the Abu Gabra–Bentiu sequence comprises four petrographical microfacies, which consist of two reservoir rock types (RRTs). RRT1 is composed of quartz arenites and RRT2 is composed of quartz wackes. The greatest storage, flow capacities, and reservoir quality are assigned for RRT1 due to its good-to-excellent porosity (average ∅ = 26.7%), permeability (average k = 1365 md), reservoir quality index (RQI, average = 1.43 μm), flow zone indicator (FZI, average = 3.66 μm) and discrete rock type (DRT, average = 13). The relatively low-to-fair reservoir quality of the Abu Gabra Formation (average ∅ = 13.2%, average k = 14.7 md, average RQI = 0.17 μm, average FZI = 1.05 μm, and average DRT = 10) is due to authigenic kaolinite and siderite content, compaction and cementation by silica and clay patches.

Antiallodynic and Antihyperalgesic Activities of Fentanyl-Loaded Dermal Clay Dressings in Rat Model of Second-Degree Burn Injury

Second-degree burn injury is the most common type of burn injury, which usually takes 2-3 weeks for complete healing. However, such patients suffer with intense pain associated with development of hyperalgesia and allodynia. Here, we prepare a silver clay patch using montmorillonite clay, betaine, and silver nitrate. Later, the silver clay patches were loaded with fentanyl. Furthermore, the patches were fabricated into burn wound dressings. The dressings were first subjected to ex vivo skin penetration studies and were later evaluated for thermal hyperalgesia and mechanical allodynia using second-degree burn injury rodent model. Our results show that application of fentanyl-loaded dermal clay (FLDC) dressings for 3 h showed significant increase of paw withdrawal latency (p <0.001) against hyperalgesia starting from 30 min after removal of patch to up to 6 h. Similarly, the FLDC dressings also potentiated the paw withdrawal threshold for up to 4 h after application (p <0.001). From these studies, we can conclude that FLDC dressings are ideal topical formulations for better management of pain in second-degree burns.

Direct pore-scale reactive transport modelling of dynamic wettability changes induced by surface complexation

Abstract Laboratory experiments have shown that oil production from sandstone and carbonate reservoirs by waterflooding could be significantly increased by manipulating the composition of the injected water (e.g. by lowering the ionic strength). Recent studies suggest that a change of wettability induced by a change in surface charge is likely to be one of the driving mechanism of the so-called low-salinity effect. In this case, the potential increase of oil recovery during waterflooding at low ionic strength would be strongly impacted by the inter-relations between flow, transport and chemical reaction at the pore-scale. Hence, a new numerical model that includes two-phase flow, solute reactive transport and wettability alteration is implemented based on the Direct Numerical Simulation of the Navier–Stokes equations and surface complexation modelling. Our model is first used to match experimental results of oil droplet detachment from clay patches. We then study the effect of wettability change on the pore-scale displacement for simple 2D calcite micro-models and evaluate the impact of several parameters such as water composition and injected velocity. Finally, we repeat the simulation experiments on a larger and more complex pore geometry representing a carbonate rock. Our simulations highlight two different effects of low-salinity on oil production from carbonate rocks: a smaller number of oil clusters left in the pores after invasion, and a greater number of pores invaded.

Micromorphological Study of Concotto Surfaces Protected by the Avellino Eruption in 3945 ± 10 cal. BP at the Early Bronze Age of Afragola Village in Southern Italy

ABSTRACTThe term Concotto refers to fragments or patches of hard heated clay that derive from living surfaces, walls, and ovens. Concotto fragments are found throughout the Italian peninsula and date from the Neolithic to the Iron Age. Current studies express contradictory opinions about whether or not the Concottos on living surfaces represent intentionally constructed surfaces or the secondary products of the contact between hot embers and sediments. This study uses micromorphological analysis to investigate the function and composition of Concotto surfaces from several domestic structures at the Early Bronze Age village of Afragola in southern Italy. Afragola is an exceptionally preserved agricultural village that was covered by almost 1 m of volcanic ash during the Vesuvius eruption in 3945 ± 10 cal. BP. The Concottos at Afragola are hard, red surfaces that are typically associated with burned materials. Micromorphological analysis reveals that the Concottos were intentionally made by laying down patches of clay and then heating them to create a hard, flat surface. This study explores the potential uses of the Concotto as cooking surfaces during the Early Bronze Age of southern Italy.

Evaluation of lidocaine loaded clay based dermal patch systems

The objective was to evaluate anti-nociceptive activity of a novel clay based dermal patch system for potential use in first degree burn wounds. First, clay patches with silver were formulated for antisepsis. Subsequently they were loaded with 5 mg/cm2 of lidocaine. The skin penetration studies were performed to ensure the delivery of drug into the skin. Finally, the lidocaine loaded silver clay patches were screened for in-vivo anti-nociception using hot plate analgesiometer in rats. The lidocaine loaded silver clay patches did not show anti-nociception after 6hrs of application despite significant amount of drug release observed in in-vitro studies. To discover the reason for failure of the patch system in thermally induced pain model, mechanistic studies were performed using clay patches not loaded with silver colloid. When lidocaine loaded clay patches, devoid of silver were subjected to in-vivo evaluation, a significant anti-nociceptive activity was observed. The reason for masking of anti-nociceptive activity of lidocaine in the silver loaded patches was potentially due to coating of silver on the paw rendering the skin more conductive. Often, additional mechanistic studies are required to be performed to critically assess the in-vivo data.

Mechanisms of clay smear formation in unconsolidated sediments – insights from 3-D observations of excavated normal faults

Abstract. Clay smears in normal faults can form seals for hydrocarbons and groundwater, and their prediction in the subsurface is an important problem in applied and basic geoscience. However, neither their complex 3-D structure, nor their processes of formation or destruction are well understood, and outcrop studies to date are mainly 2-D. We present a 3-D study of an excavated normal fault with clay smear, together with both source layers, in unlithified sand and clay of the Hambach open-cast lignite mine in Germany. The faults formed at a depth of 150 m, and have shale gouge ratios between 0.1 and 0.3. The fault zones are layered, with sheared sand, sheared clay and tectonically mixed sand–clay gouge. The thickness of clay smears in two excavated fault zones of 1.8 and 3.8 m2 is approximately log-normal, with values between 5 mm and 5 cm, without holes. The 3-D thickness distribution is heterogeneous. We show that clay smears are strongly affected by R and R' shears, mostly at the footwall side. These shears can locally cross and offset clay smears, forming holes in the clay smear, while thinning of the clay smear by shearing in the fault core is less important. The thinnest parts of the clay smears are often located close to source layer cut-offs. Locally, the clay smear consists of overlapping patches of sheared clay, separated by sheared sand. More commonly, it is one amalgamated zone of sheared sand and clay. A microscopic study of fault-zone samples shows that grain-scale mixing can lead to thickening of the low permeability smears, which may lead to resealing of holes.

Study protocol for a single-blind, placebo-controlled randomised trial of Tianjiu effects in patients with intradialytic hypotension

IntroductionIntradialytic hypotension (IDH) is the most frequent complication of haemodialysis (HD) and may contribute to cardiovascular events and high mortality. The aetiology of IDH is multifactorial; therefore, it remains a...

THE TECHNOLOGY OF POTTERY PRODUCTION OF THE POPULATION OF THE ALAKUL CULTURE OF THE SETTLEMENT NIJNEINGALSKOE-3 IN THE LOWER TOBOL REGION

The article is devoted to the analysis of the technology of pottery production of the population of alakul culture of the settlement nijneingalskoe-3 in the lower tobol region. the analysis is made within the framework of historical and cultural approach and the structure of the pottery industry, developed by a.a. Bobrinsky. as a result of the study of the pottery revealed that the potters of alakul culture selected natural iron- enriched clay and silty clay containing natural admixture of rivers shell. during compiling of molding masses most often the potters used a fire clay and various organic additives, rarely they used a gruss and calcified bone. in the collection there are just 3 of the bottom part of the vessels, which gave information on the construction aseed-body. they were made from clay patches in accordance with the bottom-capacitive program. the hollow body of the 10 vessels was made with clay patches too. the surface of vessels were treated with wooden and bone spatulas, stamps and cloth or fingers of potters. after smoothing the surface, and in some cases the inner surface of the vessels was glossing on the dry basis. Firing of finished products was manufactured in a simple piles or hearths. Following the results of the comparative analysis of the pottery traditions of the settlements citizens, their mixed characters in selecting the plastic raw material and composing the molding masses havebeen discovered. the comparison of the data with the technological information about ceramics assemblages from the neighboring regions showed that the citizens of the alakul culture are considered to be aliens on the territory of the lower tobol region.

Microzonation of seismic and landslide prone areas for alternate highway alignment in a part of western coast of India using remote sensing techniques

West coast of India is a narrow and linear, a portion from Bombay to Goa in this track is known as Konkan coast. Remotely Sensed geocoded data from IRS-1B has the potentiality in identification of localized patches of change in environmental parameters, which includes changes in lineament pattern, vegetation anomaly, rock debris and occurrence of landslides. Ground protuberances in this terrain are important surface manifestations of probable seismic activity. In these areas quaquaversal drainage pattern is inferred. Landslides are also expected in places near NH-17 (National Highway — 17) which may affect the socio-economic scenario of area. Alternate highway alignment is planned based on least hazard potentiality of the terrain. Weathered Basalts inferred, near the bank of Amba river, were not recommended for tunnel construction. Anomalous clay patches need more care for road construction. Inferred joints, fractures and faults were found in some places which were marked as hazardous locations. Some areas were marked hazardous for road construction due to the presence of palaeochannels but the same were marked as potential areas for ground water exploration.

Competition from large males and the alternative mating tactics of small males of dawson’s burrowing bee (Amegilla dawsoni) (apidae, apinae, anthophorini)

Males of Dawson’s burrowing bees (Amegilla dawsoni) search for virgin females at three locations: (1) open clay patches where females are emerging from underground brood cells, (2) the vegetated peripheral zone adjacent to emergence areas (through which females pass after emerging), and (3) clusters of flowering plants, which are often some distance from emergence areas. Males of Dawson’s burrowing bees exhibit a size dimorphism with large major and small minors. Major males patrol only the open emergence sites, whereas minor males may be found in all three locations. Although most females are mounted and presumably mated immediately upon emergence, some are not, and these females make up a pool of potential mates for the small males patrolling the peripheral zone and flower patches. The density of males at emergence sites and the probability of male-male aggression change over the course of a day and over the entire flight season. When the level of competition is low, some minor males hunt for mates at emergence areas, where potential mates are relatively numerous. But when the presence of many large rivals makes it unlikely that a small male can avoid being displaced from emerging females, minors make the best of a bad job by shifting to areas where majors are absent.

Multiple Applications of Dipmeter Curves for Analyzing Evaporite Formations: Examples from Paleogene of Bresse Trough, France

The microresistivity curves recorded by dipmeters give much diverse information about evaporitic formations because these curves have a fine vertical resolution (approximately 1 cm) and show the very high contrast in resistivity between evaporites (with high resistivity) and clay and carbonate rocks, which are porous and conductive. Examples are taken from the Paleogene salt sequence and its overlying formations of the Bresse Trough in southeastern France. The consistency of the 4 to 8 dipmeter curves allows clear recognition of different salt facies (primary salt, secondary salt, and mixed patches of clay and carbonate within displacive halite layers) and sulfate facies (massive anhydrite, nodular anhydrite, etc). The correlation of thin continuous carbonate and clastic beds using resistivity curves discloses, with a high degree of precision, the geometry of the various formations between wells. Examples show the detection of small-magnitude halite dissolution (a few meters vertically) and the lateral effect of anhydrite hydration. In this paper, a method is proposed for determining structural dip of salt beds by computing dip angle and azimuth of thin conductive beds within the salt using the DUALDIP computer program. A frequency distribution plot of these dip angles and azimuths gives a good indication of the dip of the salt beds.

Miniature mud volcanoes and other injection features in tidal flats, James Bay, Québec

Miniature injection features, including mud volcanoes, dikes forming polygonal patterns, and isolated patches of clay, occur in tidal flats along the east coast of James Bay. They are formed by localized upward ejection of a mixture of fluidized marine clay, silt, and fine sand through a surficial recent mud deposit. Liquefaction is related to the melting of ice in the clayey deposit. Upward flowing of clay, silt, and fine sand seems to result from overloading by the overlying sediments having a higher degree of density, and possibly also by pressures of ice floes or/and icefoot.

Gardening Bookshelf

MY CHILDHOOD WAS SPENT in an upstairs flat in a London suburb and apart from enjoyable days during the First World War watching my father cultivate his allotment I grew up with little experience of the skills of gardening. It has all had to be learnt by poring over books, picking up hints from gardeners, observing other people's gardens and by experimenting and learning by trial and error. Over the years my gardening bookshelf has become filled with much thumbed volumes that have grown into well‐loved friends. The older I grow the more I realize that gardening can only be learnt by experience, by knowing your soil, the corners of your garden where the sun shines all day or where the damp collects, where there are patches of clay or where the convolvulus and mare's‐tail will appear year after year however rigorously the weeding is done. But every year with the changing seasons I take down the old books and refresh my memory over small details of times of planting, depths, spacing, or proportions for potting composts. In recent years as chemical aids and labour saving devices flood the market I know that I shall not be able to find out about hormone rooting powders, peat pots or insecticides from my books but I can borrow those I need from the local library. I have come to prize my gardening bookshelf more for the memories it brings me of hours spent in our family garden than for the practical content.

Stensatte Jernalder-Kældre i Vendsyssel

Stensatte Jernalder-Kældre i Vendsyssel

Striber på kryds og tværs

Criss-cross FurrowsPlough Furrows under a Stone Age-barrow in Jutland.At Aldrupgaarde (Hvorslev parish, Viborg county, North Central Jutland) a completely razed Single-Grave tumulus was investigated in the spring of 1954. The excavation revealed an almost undisturbed grave, located upon the original ground surface. It was surrounded by a rectangular framing of stones, inside which were found the remains of a plank coffin which had been supported on each of the longer sides by two posts (Fig. 2).The post holes appeared as concentric circles with a dark core, which presumably represents the decayed post, while the outer rings are the traces of a preliminary boring and of iron deposition respectively. The full diameter of the post holes is 20-25 cms., while the depth of the two southern holes is 0.64 and 0.48 meters respectively (Fig. 3).The body lay directly upon the original ground surface on its right side with its head to the west. The skeleton was completely decayed but showed as dark bands (Fig. 2).The furnishings of the grave (Fig. 4) consisted of a thick-butted axe, 16.4 ems. long, slightly curved longitudinally and of a typical Single-Grave pattern, and of a little fragment of a flint blade. The axe lay before the head of the deceased with the blade towards the face. The flint blade lay by the western end of the grave.The dating of the grave to the Late Under-Grave or Early Ground-Grave phase is based on the type of grave, the position of the body and the burial furniture 1-7).The most important result of the excavation was the discovery of a network of plough furrows beneath the grave and over the whole excavated area (Fig. 1). In the light subsoil, consisting of sand with patches of clay, the plough furrows stood out as a criss-cross of stripes. The width of the furrows varied between 3 and 10 cms., and the average distance between them was 30 cms. The directions of ploughing were E-W and NNE-SSW.A section through a series of furrows (Fig. 5) shows that the maximum depth in the sub soil which was reached by the ard was 9 cms., and that the cross-section of the furrows has the shape of an oblique angle with one side steep and vertical and the other curved and gently sloping.The furrows are dated by the grave which gives a terminus ante quem for the ploughing. They therefore provide the earliest definite evidence for the use of the plough in Europe. It is moreover believed that the furrows belong to the Single-Grave culture. This culture is represented on the site by culture remains in the body of the mound and by three further Single-Grave tumuli in addition to the one excavated. In the vicinity the Single-Grave culture was dominant since the Under-Grave phase. From the same phase of development of the Single-Grave culture come the earliest impressions of corn in pottery yet demonstrated 8). In Europe prehistoric fields have not yet been traced further back than to Late Neolithic times. In Denmark the presence of fields in this period has been seen in the heaps of stones collected from the fields9), and in England in the form of irregular field systems surrounded by baulks10), while in Holland and. in Norway Late-Neolithic plough furrows have been found 11).In agreement with P. V. Glob's hypothesis 12) the presence of "shoe-last wedges" is believed to demonstrate that agriculture and the plough were in­troduced simultaneously in the area of Europe dominated by the Danube cultures. Discoveries of shoe-last wedges in Denmark is taken as an indication that the same situation may have operated in Denmark 14a), though the Danish shoe-last wedges may have been first introduced as late as the Middle Neolithic Period 14b)The oblique angle of the cross-sections of the Aldrup furrows agrees with the cross-sections of the Early Bronze Age furrows from Sevel16), with the marks of wear on the shoe-last wedges and with the Iron-Age ploughshares found in peatbogs 17). As a result of these correlations it is believed that the furrows were made by a crook-ard which was held somewhat obliquely during ploughing.The discovery in recent years of plough furrows under Bronze-Age tumuli has shown that the cultivation of heavy clay soils began as early as the Early Bronze Age, with the ard as the ploughing implement20). The Aldrup furrows suggest that heavy soils may have been cultivated as early as Middle Neolithic times, as the subsoil changes from sand to clay only a few yards from the tumulus.P. Kjærum

Palæolithic Implements, etc. from Hackpen Hill, Winterbourne Bassett, and Knowle Farm Pit (Wiltshire)

Implements are described from the localities mentioned in the title, which lie at heights of 885, 576, and 450 feet above O.D. respectively. Hackpen Hill forms a ridge of Chalk running north and south, capped by patches of Tertiary clay. Trimmed stones of eolithic nature were obtained from fields ploughed in Drift-gravels, together with abraded Upper Greensand chert, quartzite-pebbles, and small flints. The greater number of the flaked stones were found within and near shallow pits excavated in yellow Drift-clay, apparently newer than the Red Clay with Flints, exposed at the edges of the larger hollows. The implements are unabraded, abraded, and striated; some stained brown, some green, others unstained; evidently some are in situ , others were brought with the Drift. Implements taken from the clay are described, and a distinction is made between the palæoliths and neoliths obtained from the same surface. The similarity in the mineral condition of the former to palæoliths from Knowle Farm Pit is pointed out, and both are referred to the Chelléen period. It is noteworthy that, while implements and flakes are numerous on the top of Hackpen Hill as compared with good, trimmed pieces, yet at this 570-foot level on the Winterbourne-Bassett plain implements and flakes are very scarce, while trimmed pieces are very numerous, although the level of the Winterbourne stones is 300 feet lower. Many of the latter, however, have been evidently rechipped, and are therefore of later date. The Author concludes that implements of at least three palseolithic periods are

The Plans of a New Asylum for East Sussex

When East Sussex determined a year or two back to build an asylum for its sole use, a Visiting Committee, appointed for the purpose, was fortunate enough to find in the centre of the county a suitable estate which the County Council purchased. It is situated at Hellingly, a village about nine miles north of Eastbourne. The area is four hundred acres, compact, as you will see on the plan, having within 400 yards of its western boundary a railway station which we propose to connect with the main asylum by a full gauge tramway. It slopes gently upwards from the south towards the north, where it attains its highest level of about 130 feet above the sea. The subsoil is most favourable, being, with the exception of two patches of clay, of a sandy or gravelly nature. The water supply is adequate, and the general contour lends itself readily to an efficient system of drainage, which will be bacterial. The views are excellent, extending to the sea and the south downs. It would be difficult to find a more suitable site for an asylum. A sub-committee was authorised to travel about the country to inspect other asylums, I being appointed its chairman. We visited the Hartwood, Lenzie, Gartloch, Hawkhead, Cheddleton, Burntwood, Glamorgan, Dorchester, Isle of Wight, and Chichester Asylums.

Introductory notes

I. The Physical Features of Kerguelen Island. Kerguelen Island is little else than a succession of hills and mountains formed almost exclusively of volcanic rock. In its greatest diameters it measures about 80 miles from N. W. to S. E., and 70 from N. E. to S. W., but no part of the interior is farther than 10 or 12 miles from the sea, for the coast on all sides is exceedingly intricate and abounds in large inlets and narrow fiords, which run far inland at frequent intervals between ranges of precipitous hills. A district of considerable extent in the midst of the island is occupied by snowfields, whence glaciers descend east and west towards the sea. This district is hounded on the S. E. by a series of snow-clad mountains and lofty hills extending in a curve northwards from Mount Ross almost across the island. The area intermediate between this range, Royal Sound, and the Mount Crozier hills, and likewise the islands in Swains’ Bay and Royal Sound, contain series of interrupted ridges, the majority of which are crowned and terraced horizontally with basalt more or less amygdaloidal, and rarely exceed 600 feet in altitude. Their south-eastern and eastern slopes are generally very favourable for vegetation, being sheltered from the prevailing winds ; but scarcely any of them attain to heights sufficient to he suitable for the growth of plants restricted to elevated sites in this island. The Mount Crozier hills, and those on the opposite side of the sound, are upwards of 2,000 or 3,000 feet high. Their summits are covered with snow until late in the season. Most of them are massive and rather simple in contour, but near Mount Crozier a few of the peaks are singularly picturesque, bristling with pinnacles, needles, and castellated towers of rock, some of which are visible from the southward, but not many. A similar departure from the prevailing type of Kerguelen Island scenery is noticeable among the hills near Sprightly Bay, and the aiguilles on the south side of Mount Ross. An active volcano is reported to exist in the neighbourhood of Bonfire Beach, and at one or two places on the same side of the island it is said that there are hot springs, resorted to by the sea elephants for the purpose of recreation at certain seasons of the year. A cold mineral spring oozes forth at the head of a small patch of boggy ground very near the western terminus of Swains' Haulover. It lies within a stone’s throw of the sea, in a line with the nearest end of one of the nameless islands in the bay and the apex of the semi-pyramidal extremity of a high precipitous hill, which constitutes a conspicuous landmark on the opposite shore. The water is free from smell, but has a pronounced mineral flavour, seemingly of alum. On the steep slopes bordering Royal Sound, near Swains’ Haulover to the S. E., two or three small patches of yellow clay are visible. The clay appeared to include nothing but small fragments of volcanic rock, similar in composition to the masses in sitû around it. A little farther on, along the same shore, opposite the south-eastern point of Seal Island, one of the hills is intersected by a nearly vertical wall of trap conspicuous from the intervening channel.

On the Nature, Correlation, and Mode of Accumulation of the Drift Deposits of the West Riding of Yorkshire; with remarks on the Origin of Escarpments, Valleys, and Outlet Gorges, and an Appendix on the Cliffs of Plumpton, Brimham, Goredale, and Malham

[ For Plate and Explanation see Close of this Paper. ] For the last six months I have been devoting almost undivided attention to the classification and correlation of the drifts of the West Riding, between York and Settle in one direction, and between Ripon and Barnsley in another. I started with the idea, which subsequent observations have confirmed, that it is only by a comparison of the characteristics of the drifts on plains with those in valleys and on hill sides that we can arrive at correct notions of the mode of their accumulation. CLASSIFICATION AND DESCRIPTION OF THE DRIFTS OF THE WEST RIDING. 1. Greyish-blue and Variegated Boulder-Clay. —So far as I can ascertain, it is to the late Mr. Teale, of Leeds, that we are indebted for the discovery of two lower boulder clays, the blue and the yellow. He found patches of blue clay at New Wortley, Nether Green, Woodhouse Moor, Adel, and Yeadon Colliery, at various levels, and at Adwalton at a height of about 600 feet above the sea. At nearly all these places he found the blue clay overlain by the yellow clay. I have traced the existence of blue clay up the valleys of the Aire and Wharfe, and on the plain of Craven, where it is extensively developed. At lower levels, to the south-east and north of Leeds, it exists only in patches. In the north-west part of the West Riding, where it lies near to, or on the carboniferous limestone, the stones ...

II. On some supposed Ice-scratches in Derbyshire

In the number of the GeologicalMagazine for last August, in a letter from Mr. Mackintosh, there is a notice of some markings, supposed to be glacial, on a rock known as ‘The Bloody Stone’, between Cromford and Bonsall, in Derbyshire. Mr. Mackintosh's language is not very clear, but I rather gather that he has doubts whether these markings were really made by ice: nor does he seem to be aware of the great interest that would attach to the discovery, if it could be proved beyond question that we have here a true ice-marked surface of rock. It is, I believe, very generally the case that the deposits and, so to speak, footmarks of the Glacial epoch are found on the western side of the central axis of the north of England in much greater force than on the eastern side. Thus much I can say from personal observation: in North Staffordshire and Lancashire, boulder-clays and gravels are found stretching from the plains far up the hill-sides, and erratic blocks lie here and there upon the moors to a height of 1,400 feet above the sea. On the other side of the socalled Pennine Chain, however, the case is widely different: through-out the whole of North Derbyshire and the adjoining uplands of Yorkshire there is nothing that can be safely set down as Drift, and certainly no blocks or pebbles of foreign rocks over the country to the north of the Wye. The valley of that river cuts right across the Great Saddle; and along it, and to the south of it, we do find stray patches of clay with ice-scratched boulders, mostly of limestone, but here and there of granite, greenstone, and other strangers, which seem to have found their way from the west along this sole opening in the barrier which elsewhere blocked up their path. ‘The Bloody Stone’ is just a case in point, lying as it does in the valley of the Derwent, about seven miles below the junction of the Wye with thatriver. I was, therefore, extremely glad to see Mr. Mackintosh's letter just in time to pay a visit to the spot, and I shall tell as carefully as I can what I there saw, in hopes that more experienced ice-men, if they cannot go to see for themselves, may be enabled to decide whether we can fairly refer the markings in question to the action of ice.