E. T. NEWTON ON ISCHYODUS TOWNSICNDII. 119

the outer corner of the median tooth; it may well be, therefore,that the portion of the median tooth in the Upway specimen,which seems to be partly separated from the rest, may be therepresentative of this anterior outer tooth, and would probablybecome more distinct as the creature increased in size. Again,the beak tooth in the Upway specimen does not show the samedivision into separate portions as it does in the larger specimensof T. Townsendii; but this also may be due to the specimen beingpart of a young individual. On the whole, this Upway fossilagrees much more closely with 1. Townsendii than with any otherspecies, and, in spite of the above-named differences, I do notfeel any hesitation in referring it to that species.

Ischyodu8 Townsendii is only known as a Portland Oolite species.The type was obtained from Great Milton, near Oxford, and thereis a second mandible in the British Museum from N. Wilts; inthe collection of the late Sir Philip de M. Grey-Egerton, Bart.,there is a premaxilla, and we have now to add the third mandiblefrom Upway. Curiously enough the remains of this species havebeen found much more abundantly as derived-fossils in the peculiarNeocomian deposits at Potton and Upware, The only knowledgewhich we have of the form of the maxilla is derived from a rolledspecimen obtained at Potton. (Vide Memoirs, Geol. Surv., Mono­graph 4, page 35.)

A GEOLOGICAL TRIP IN COLORADO IN 1880.

By S. R. PATTISON, ESQ., F.G.S.

The Geology of Colorado has been well known since the year1867, when Mr. Hayden, U.S. Geologist, undertook the survey,and published in 1873 the first of the remarkable series of volumeswhich have made the structure of America so plain to us, and dis­closed a startling array of facts concerning the newer world beyondthe Missouri.

On going westward from Chicago, the traveller enters the flatcorn and wheat lands which extend away to the north-west. Allfeatures are by degrees left behind save the boundless plain. Onnearing the Missouri, we discern a broken line of low bluffs, amidstwhich the city of Council Bluffs tells by its name of the vain re­monstrances of the Indians on being obliged to begin their con-

120 8. R. PATTISON ON A GEOLOGICAL TRIP

tinuous retreat towards the setting sun. Whilst changing fromthe Eastern line into the Union Pacific, we may note for a momentthe features of the bluffs within sight. These are composed ofyellow marl, and are the sides of a river valley excavated in whatSir Charles Lyell terms loess. This was deposited after the pre­sent surface was fixed; but there has been certainly one, and pro­bably more than one, elevation since the deposition, for aboveDecatur, where the banks are formed of cretaceous sandstones,the Indians have made inscriptions on them. Mr. Haydensays :-" Many of these hieroglyphics are in positions totally inac­cessible to the Indian at the present time. None of them nowIiving know anything about them, and it is supposed that they mustbe very ancient, and that, since they were made, great changesmust have been wrought in these bluffs by the waters of the Mis­souri. It seems strange that none of these hieroglyphicalwritings, which occur quite often on the chalk-rocks of the Niobraragroup, higher up the Missouri, are known to any Indian nowliving. Marnel's Creek is called, in Dakota language, the creekwhere the dead have worked, on account of the markings on therocks."

The broad valley of the Mississippi was a lake whose sedimentsnow reach, in some places, a thickness of 150 feet. In these arefound shells of existing fluviatile molluscs, bones of the Mastodon(Elephas Americanus) and its allies, with some remains of presentmammalian forms. The bones are found chiefly in the lower partof the deposit, which also contains boulders from the distantRocky Mountains, stretching in diminishing size and numberseastward from the foot of the ranges for about a thousand miles.

Below the loess are beds of carboniferous limestones on theeast, succeeded by tertiary clays towards the west.

From the Missouri the prairie country stretches uninterruptedlyon every hand. The direct westward track by rail to the foot ofthe mountains is 650 miles, with a grade apparently level, butreally rising imperceptibly until at Denver it has risen 5,197 feet.Throughout all this traverse the strata lie nearly horizontal untilwe near the foot of the mountains, when they are lifted to a highangle and tilted against the metamorphic and gneissic bosses ofthe great hills. On the prairie we get but few opportunitiesfor geological observation, The surface soil is for the mostpart a distinct covering of good dark mould, with small angular

IN COLORADO IN 1880. 121

pebbles. On the river banks this appears to be often 30 feet inthickness, and is of fertility practically inexhaustible. Beneaththis, and often inseparable from it, is a small loamy deposit of theloess referred to just now. In some places the lower, pebbly por­tion of this forms the surface. It is in this, the great Mastodongravel, that a few, very few, traces of man have been found. Thecourse of the rail brings us on to the line of the Platte river afterabout two days' travel. It is a constant, but very shallow stream,fringed with wood-a welcome sight-and with reeds and tallplants. Its average width is three- quarters of a mile, and itsaverage depth only six inches I This reminds us of some of thethin freshwater beds of the old rocks, produced by the periodicoverflow of shallow waters. As we now see occasional breaks, anddiscern several formations, it will be a convenient point for sum­marizing the sedimentary strata of the great tertiary central area ofNorth America, which is old tertiary. All the upper beds showfresh-water molluscs, but change to brackish conditions withoysters of tertiary types, and with several alternations of marinebeds in the descent towards the cretaceous series. In tertiary timesthis must have been a land of lakes and islands, and occasionalmarine occupation, As we examine the successive developmentof clays and sands, we soon learn that the three great divisions ofthe tertiary established by Sir Charles Lyell are equally conve­nient here as an artificial index.

The Eocene is here called the Lignitic group, the upper portionof which (Oligocene 1) is distinguished by a large and beautifulflora, comprising fan-palms and tropical forms, and containing alsoremains of the hippopotamus and sabre-toothed tiger, and bedswith river shells. The uppermost portion of this is a fresh-waterstratum with bones of turtle; next above comes a full Miocenegroup, composed of limestones, sands and clays. The fauna is allextinct, including Machairodus, Rhinoceros, Cheiropterus, and. themarvellous collection of mammals described by Professor Marshand now at Yale College, with silicified woodand a large, fine flora.

Succeeding this upwards, on the Platte river, is a Pliocene de­posit with bones of Canie, Felis, EquU8, &c., scarcely distinguish­able from modern species. Within this, and rising in very irre­gular masses, occurs the area of our chalk and greensand. Thehigher beds of the cretaceous series met with on the Missouri, andagain near the Rockies, are Belemnite-sandstones, with bones of

122 S. R. PATTISON ON A. 'GEOLOGICAL TRIP

Mosasaurians and numerous fossils. Under th ese are plasticclays, with Nautilus Dekayii and another form of Mosaseurian.A barren middle zone separates the fossiliferous beds. There &rechalky beds, with oysters and fish scales; underneath these arestrata. containing Inoceramus problematicus, Nautilus eleqans,Scaphites Warreni &c., in grey clays with thin coloured limestones,appearing to be on a level with our upper greensand. I sawnumerous fossils at Manitou from th ese beds.

Lowest of all is the Dakota group, with its lignites and re­markable assemblage of plants, well known to us through thelabours of Hayden and Lesquereux, Thus, whilst the upper cre­taceous is disturbed and mixed, the lower is a tranquil sediment.

The Dakotagroup in its marine beds is known by the forms ofInoceramus and its associates; but the sandstones contain saurianremains and a flora remarkable for its richness in dicotyledonoustrees. The latter record here their first appearance, in force, on theearth by a sudden burst so far as we know at present. The leavesand fruit have been described by Lesquereux in the publieatious ofthe States Survey, and denote a sub-tropical vegetation, differingwholly of course from those now growing, though remarkablysimilar. They comprise cinnamon, laurel, sassafras, magnolia,and other well-marked forms. These rocks have a very wide ex­tension along the base and amidst the inlets of the Rocky Moun .tains,

Inside these again is It grand exposure of triassic beds, reducedto discontinuous fragments by inconceivably powerful denudation.They form a broken necklace as of dark red coral around the foothills, and constitute the monument series, as it is called. MonumentPark displays huge lumps and needles of th ese variegated redrocks, comprising coarse pudding-stone or conglomerate, and everygrade of sandston e. This is occasionally capped with basalt, and isthus protected, exactly as is the chalk in Antrim. These shapelesslumps are favourite ohjects with photographic artists. They consti-.tute the peculiar scenery of the" garden of the gods j" there theyare flanked on the one side by cretaceous layers, and on the otherby some coal-measure grits and limestone, but all so tilted andnaked as to compose very singular landscapes. Mr. Hayden,speaking of the erosion of the Trias, says :-

I' Whatever may have been the agents which in times past have

IN COLORADO IN 1880. 123

wronght ont all these remarkable forms, it is plain that they haveacted in former times with far more intensity than at present."

In this part of Colorado the Trias is the most extensive of all thesedimentary unmetamorphosed formations; but it is so remarkablydenuded as to display a surface like the monuments of Carnae inBrittany.

The uplift of the mass of the Rockies must have preceded theTrias, for the great conglomerates of the latter were formed whenthe metamorphic and granitic rocks of the main chain constitutedthe coast line, and these pebbles were the shingle beaches.

Resuming our route-which we have anticipated by some hun­dreds of miles-we observe between Cheyenne and Denvermuch surface-blown sand. There are sand-fences put up todefend the line of railway from invasion by drifts at particularpoints. Here, too, we pass desert places where the soil is so alka­line that nothing but the sorriest grasses and scrub can manage tolive.

I omit all mention of the great mining centre; man aud his workare too recent here to be interesting. It is the capital of a Statewhich boasts of a number of mountain peaks above 14,000 feethigh, 200 between that and 13,000, and an innumerable forest oflower heights and rock masses with canons, having nearly perpen­dicular walls of a thousand feet and upwards, and in some casescanon within canon. Ever since the discovery of a silver lode in1869, it has been, as it is now, the scene of active mining enter­prises.

On leaving Denver again for the north-west, we run along thefront of the mountains and reach the foot-hills at Golden. AtGolden the sedimentary rocks have been removed, leaving the greathard red rock as tumbled foot-hills at the base of the grey quartzosegneiss and granite. Outside the former are fragments of creta­ceous strata; the gneiss abounds in quartz veins, from the con­tents of which the place derived its name. Golden is outwardlydistinguished by its tall chimney-stalks-tokens of considerablemanufacturing industry.

In broken lines all down the eastern front of the Rockies, coaloccurs, and is mined and used for all purposes. It is rather light,and appears to occur both in the tertiary and in the cretaceousseries, but principally in the former. It is worked a good deal,

124 S. R. PATTISON ON A GEOLOGICAL TRIP

being opened as fast as the railway system extends. The produc­tion and sale has run rapidly up to 300,000 tons per annum. Isaw much of it on the line j it is of varying quality; but most of itis a good bituminous coal.

The usual results from productive coal measures are sure tofollow i already there are in the southern borders of Colorado ironfurnaces, a Bessemer st eel plant, and a rail factory.

Weare now near enough to the mountains to see their structure.Granite constitutes the central mass, bald at the summits, brokenand grey, but oxidised into red in vast ranges. Piled up againstthis, and often covering -it, are old gneissic and metamorphic rocksof varied hue and form, and still more highly coloured and brokenare the secondary and tertiary rocks of the foot-hills, varied bylong lines of forest and grassy terraces overlooking the plain, andby the dry lake-basins which constantly occur among the moun­tains, and constitute a leading feature of the scenery.

The chain is crossed occasionally by transverse ranges, andbroken through by the grand fissures throug-h which the riversrun. Here and there are bands and bursts of brappean rock. Thewidth of this enormous mountain mass varies from 300 to 1,000miles, and in length it appears to stretch from the Arctic circle tothe tropics.

In approaching it here, we go right into 8 scoop in the hillssurrounded by terraced slopes and diversified by jutting rocksof sandstone, and some peaks of greenstone. Occupying this isthe town of Boulder, at the mouth of the famous canon of thatname. From this place, the road up the canon having beenwashed away, we mounted a buck-board, drawn by a pair of fleetponies, and ably charioteered by Mr. Delavan Peek, of Ni-Wot,to whom an introduction proved to be a free ticket with endlesscoupons. We had to traverse the boulder-strewed plain, and makefor the parallel of Jim Creek. We then ascended that remarkablegorge. Immense masses of metamorphosed sandstone belonging tothe foot-hills first blocked the way, then the usual succession ofred schistose strata, and the grey gneiss, and lastly granite. Halfway up we came to a mica mine. The mineral occurs in a quartzrock. It is split and trimmed like Welsh slate. It is a very re­markable article and much used in powder for lubricating andpacking machinery. We had full opportunity of examining thedevelopment of placer mining. The deep deposit of irregular

IN COLORADO IN 1880. 125

gravels and sands in the gorge, cut through by the fierce stream,and cut through over and over again by the works of thegold miners, displayed all the features of the original fissure, thewearing down, deposit of debris, and successive disturbances bymen wielding hydraulic power furnished by the turbulent stream.This and a few similar passages in the course of the following daysgave me some insight into a subject deeply interesting both to thestudent of the antiquity of man and of the work of the miner.

The canons here owe a portion of their picturesque character tothe varying composition of the rocks through which they arebroken and worn. They approach the sublime in the upper reacheswhere they are frequently bounded by lofty pinnacles of greygranite rock, possessing the characteristic open joints and fre­quently springing as it were from the jagged reddened rocks ofthe metamorphic series. The frequent waterfalls and basins wheregravel has lodged, and the constant exhibition of the work of air,water and ice induce some generalisations.

Atmospheric agencies and probably occasional earth-movementshave degraded mineral veins, and decomposing portions as well ashuge masses. These have been carried down the canons andgalleries, grinding as they go, and spreading out finer and finerdetritus in the descent. Where the parent vein contained gold ortin, specific gravity has caused it to be sorted and deposited at thepoint of least motion, and these are the rich" finds" of the goldminer, and Cornish tin streamer alike. Underneath the drift therocks are frequently said to be grooved as by glaciers, whilst thelocal accumulations and varying lines of bedding, show that thevalleys were frequently gorged with ice and scoured by floods.

But amidst this apparent confusion there appears to be evidenceof two very distinct and distant periods of action, one apparentlycoeval with the glaciation of the rocks, or nearly so, the other sub­sequent, and clearly belonging to the time of present levels, andconfiguration and height of the valleys.

The upper reaches of the forest brings to view a generalfeature which was novel to me, namely, a broad belt of atleast three miles wide, of slaughtered trees, lying prostrate aswhitening skeletons in every stage of decay. The timber line ishere 11,000 to 12,300 feet high. The pines, growing on the last3,000 feet, yield to extremes of wind, and of course the weakest,i.e., the highest, are the feeblest. Thus the number of the skeletons

126 s, R. PATTISON ON A GEOLOGICAL TRIP

increases with the height and the mountains are all closely girdledby them, the living trees predominate downwards until theghastly whiteness which prevails at the top is succeeded by thenormal green of the lower forest. The snow lies in patches aboutand above 14,000 feet . The flora up to this is abundant andbeautiful.

On we went through the solemn forests up to Ni-W ot, where ina comfortable log-house, at an elevation of about 10,000 feet, westayed some days in perfect mountain solitude.

We were near the great Columbia vein, in fact on it , and I wentdown into it at Ni-Wot, and at a mine called Nelson on a parallellode. The lodes were true fissures, nearly vertical, one wall wasapparently a porphyritic trap, the other coarse metamorphosedschist, The lode stuff was quartzose and felspathic rock of loosetexture, containing coatings of pyrites in which is found thegold.

The pay vein forms only a small and irregular portion of thelode, varying from nil to 2 feet in a crevice from 12 to 20 feet wide.The copper and silver are secured as well as the gold, but the oreis very refractory and furnishes but a small quota at present of the.five million pounds sterling, now the yearly produce of the Coloradomines.

A traverse into the glacier lake district of the Arapahoes, anascent of Bald mountain, afforded an opportunity of seeing theupper scenery of the Rockies, which is well worthy of its reputa­tion. I examined several deposits of the substitutes for bogs whichis called" duff," and consists of the fallen leaves of the fir ac­cumulated in a peaty mass by the rains until it becomes of a spongytexture and holds water like a moss, and like it swells and retainsthe falling or surface waters, arid holds them as a magazine forcontinuous supply all the year through. I saw only a few spots oftrue moss, but vast extents of varying thickness of this duff. Theoccurrence of duff is another instance of the all-important func­tion fulfilled by forests in regard to climate and water supply, andthe formation of coal past and future.

I now went through some of the famous gold mining districts ofWard County. The conspicuous feature to a geologist is thecoarse gneissic and granitic rock, with bosses as though denuded,seamed with quartz veins. Descending, unwillingly, again toDenver, I went southwards by the Rio Grande Railway, through

IN COLORA no IN 1880. 127

the remarkable triassic rock exposures of " monument" to the newcity of CoJorado Springs.

Colorado Springs is favourably placed for geologizing as the foothills are much broken and tossed , and the huge mass of Pike'sPeakdisplays the fundamental rocks in a very striking manner. Thereare two stores of mineral and natural curiosities in the young city,one of which is dignified with the title of Museum on the strength ofsome unfortunate bears, wolves,panthers, and lynxes kept in durancevile in a back-yard. The display here of the large crystals for whichthe granite veins are renowned is worth attention, and here I ob­tained the plant and insect remains which I lay before the Society.They came from Florissant, a place about 30 miles up the Utepass which, unfortunately, I could not find time to visit. Thoughsmall and fragmentary they are well preserved, and to an un­skilled observer, they look like an oligocene group. Thence I wasglad to get to the upper summer resort of this district-Manitou.

The original cause of the selection of Manitou was the occur­rence of soda-springs in the line of the little stream, which isnamed from this Fontaine-que-bouille, and wss much regarded bythe Ute Indians as an outburst or speech of the Great Spirit(Manitou). The springs issue with considerable force and heatjust at the junction of the sedimentary and metamorphic rocks. Thelargest throws up five or six gallons per minute. The proportionof iron varies in the several springs, which are resorted to forcurative purposes. The Ute Indians regarded the principal springwith religious reverence, and some time after the settlers had com­menced surveying, the Indians came down one day in single file onhorseback, rode round the spring, casting into it an offering andriding away. After their visit it is said by the Government sur­veyors that over a bushel of the offerings in gold ear-rings andornaments, was taken out of the bubbling spring. The spray leavesa solid incrustation around some of the outlets.

The village is the converging point of several beautiful canonsThe one on the right is called William's Canon. The central oneis the Ute Pass, the one on the left is the Pike's Peak Canon.

In William's Canon the Jurassic rocks occur with coal andsilicified wood. The limestone caves in the vast precipices offrowning reddened rock, greatly increase the picturesqueness ofthe scenery, which has indeed all the features which an artist loves,and owing to the broken character and vertical bedding of the rocks,

9

128 s. R. PATTISON ON A GEOLOGICAl. TRIP

the geologist is furnished with constant surprises. The Silurianstrata here rest unconformably on an older schistose rock, whichmay be a member of the Cambrian. There are bars of igneousrocks broken through and worn down at the foot of the huge wallsof gneiss and metamorphosed old rocks, rendering the combina­tion, aided by luxuriant vegetation, inexpressibly beautiful.

My farewell exploit was the easy ascent of Pike's Peak up thecanon which rises direct from the end of the village, through thered rocks, and the gneiss, by the cataract of boulders fallen fromthe pinnacles above, or by veins containing huge crystals ofsmoky quartz, and of orthoclase, and other minerals, up to akind of clinker granite at the bare summit, here sprinkled withsnow. The height is 14,137 feet, and I experienced, for a fewmoments only, some pain in breathing. I need not enlarge on theview in the clear air-the mountains of San Juan, in Mexico,174 miles away in the south-the long northern range intoMontana-the prairie extending infinitely, as it appeared,on the east, with the Platte river in folds glistening on itssurface--on the west the view of the sea of mountains andparks, old lake beds, rocks, woods, and gorges, over into EstesPark-was amazingly grand and beautiful. But I must spare youany attempt at describing the indescribable. The ascent gavean opportunity of considering the canons with a view of ascertain­ing their origin.

My decided impression is that the canons were original fissures,broken and jagged, either by upheaval or depression, and erodedthrough countless ages by atmospheric agencies in the higherportions, and by the added action of streams in the lower reaches.The course and work of the last named may be traced in the drylakes and lake barriers, which now as grassy hollows dot andbeautify the scenery.

The marks of glaciation which I noted are about 1,500 feet up,i.e., about 8,000 feet above sea-level. The drifts appeared to me tobe all such as were furnished by the rocks immediately above andaround.

Mr. Hayden, in his first report, remarks that the traces of iceaction on the east show that the mountains were once much higher,and that the present high gravel ridges and buttes are the relicsof that time. That afterwards, and by long continuance of glacialconditions, immense quantities of drift were deposited, and theslowly decreasing forces produced diminished results.

IN COLORADO IN 1880. 129

One of the interesting of the many qnestions which rise out ofthe facts displayed in this district is that oCthe age of the gravels,which is closely connected with glacial phenomena on the onehand, and with the human period on the other.

It was my impression, from such examination as J could give inthe Boulder and Pike's Peak districts, that the gravels may bedivided into two series, first those which were the result of glacialaction, or action in glacial times; secondly, the results of subse­quent subaerial or physical forces. In Cornwall the tin pebbles areonly found in accumulations of the later date, probably becausethere are no glacial gravels; but in America, where there are thedebris of granitic and gneissic and metamorphic rocks spread outby the agency of ice and snow, gold is found in the gravels of bothseries . In the first it has found its primary bed, and then, onthis having been re-made by subsequent action, it is re-sortedwith additional materials. Lastly the bed has been again dis­turbed by man in his search for the nuggets of the precious metalduring nearly a thousand years. Of course the gold, being theheaviest portion of the load carried forward by the waters, wouldfall closest to the parent rock, and would be lodged in the pocketsand cheeks of the gorge, especially at the upper side of the con­tractions of the latter, or where the turbulent current was checkedby an angle in the bed. Accordingly the placer miners in onecountry and the tin streamers in the other both study the rockysides of the hollow in which they work. In the Rocky Mountainsthe slopes are so steep and the rushes of water so powerful, theeffects of present causes so intense and extensive, that it becomesextremely difficult and often impossible to separate (usingantiquated language) the diluvial from the alluvial.

Another feature which must strike every traveller is the extremerapidity with which all effects are obliterated and become nndis­tinguishable from phenomena prior in time. This of course occursin all mountain districts, but on account of the bald summits andfrequent coarse veins, and the dirt bed of a timber line 12,000 feethigh, it is eminently the case here. The flood-changes which arerare phenomena in the upland valleys of Our own country, areconstant occurrences here. The observer is soon taught that it isimpossible to tell whether he is in glacial gravels or in accumula­tions under ten years old, so rapid is the process by which naturereasserts her tranquil beauty. Hence the unreliableness of theattempt to introduce time or dates into our calculations, in regard

180 s, R. PATTISON ON A GEOLOGICAL TRIP

to any extraneous objects such as worked stones or pottery foundin the auriferous drift. When worked flints are numerous, and liejust like other pebbles, as in the gravels of the Somme Valley andEngland, we know that they are original portions of the bed, andtherefore as old as the latter. But when they are isolated finds,and especially accompanied by things believed to have been ofvarious dates, and all more or less supposably connected with goldseeking, we cannot be sure that they are contemporaneous withthe first deposit of the gravel; nay, we reasonably infer that theyare not. Hence I entirely distrust the alleged proof of antiquityclaimed for the articles which have been reported from the drifts.Like the celebrated bits of bread-and-cheese brought up in the500 feet sinking for coal, they betray their own recentness. Imean that they belong to the mammalian gravels, and are not, atmost, older than our implement-bearing gravels.

We are thus, as in Europe, brought back to the conclusion thatat a period far, very far, back through all the ages it may be of thePost Pliocene, or at some epoch in this long progression-some­times, so far as our present evidence goes, when the glacier con­ditions were yielding to more moderate temperature, and the landwas still occasionally subjected to elevations and subsidences-manappeared in both regions, as a hunter on the plains and a dwellerin the dens of the earth.

I had made these notes before I met with Mr. Whitney's recentpublication on the researches of himself and his staff amongst theauriferous gravels of the western slope of the great Americanchain. Of course it would be irrational to dispute the facts col­lected by so able and indefatigable an observer as this greatgeologist, but I must venture to say that his conclusions are notwarranted, so far as I could see, by the appearances on the easternside of the same chain. Let me recapitulate Mr. Whitney's de­duction.

First, that there was an accumulation ofwater-wom debris alongthe sides of the rivers Rowing down from the hills. Secondly,interstratified with these were heavy deposits of volcanic materials.Thirdly, there was a continuance of igneous agency. That this wasgoing on during most of the tertiary period, and is coeval with thelatter. That whilst the Eocene and other tertiaries were beingformed elsewhere, the auriferous gravels were being deposited.Fourth, that the canons were excavated at the same period,

IN COLORADO IN 1880. 131

and the causes have gone on to produce the same effects, but withdiminishing action. Fifth, that this gravel period is older thanthe glacial, and that" ice had nothing to do with any part of theerosion of the glacial period." That not until all the gravel hadbeen piled up was the higher portion of the Sierras occupied byglaciers. That all the canons had been cut out, and the wholetopography, down to its minutest details, was just what it is nowbefore icehad any existence in these parts. Sixth, that the termsEocene, Miocene, and Pliocene, have no application here, wherethere never was any tertiary. Mr. Goodyear supports this by hisstatements founded on extensive surveys in the northern area ofthe great Pacific slope. Both attribute much to the slow ordinaryaction of present causes; but both adduce interruptions byparoxysmal action. I must, in few words, say why I dissent fromthese conclusions. In approaching the Rocky Mountains from theeast I find sheets of mammalian gravel as well as sundry deposits ofbrick-earth everywhere forming the soil, and cropping up here andthere from underneath these is a great lignitic tertiary formation.The drift may be traced up to the foot of the hills, and up their lowerslopes, distinctly covering the tertiary, not as an integral portion ofthe latter, but as a subsequent mantle extending over all thetertiaries as well as the secondary rocks along the whole line.Now it is in this drifted covering that the remains of mastodon,and alleged traces of man occur, in fact it is the home of the greatmammalian fauna. Is it not inconceivable that this should happenon one side of the mountain chain, whilst the other should distinctlycontradict it?

Then as to the effectsof ice. On the eastern side I saw the lakebasins, the moraines, the scratched boulders, the peculiar arrange­ment of boulders and gravel which A.gassiz long ago taught us toconnect with glaciation. Is it possible to assign one epoch to thesephenomena on one side of the chain, and a totally different epochon the other?

If the pre-existence of man to the glacial epoch is supposed tobe proved by the contemporaneity of the gravel in which his remainshave been found with the tertiary period on the western slopes, Idemur entirely to the conclusion on stratigraphical grounds.

The published observations of Mr. G. M. Dawson, the son of Dr.Dawson, of Montreal, and Government Geological Surveyor in.British Columbia, published in the Quarterly Journal of our

132 GEOLOGICAL TRIP IN COLORADO IN 1880.

Geological Society, " On the Superficial Geology of British Columbiaand adjacent regions," also appears to be in direct opposition to theviews of the American geologist, for he says that the boulderwork of the glacial period is distinctly posterior to the tertiary,and that glacial action and its results have clearly affected theprior formation, including the pliocene. He sa1s:-" Boulder-clayis spread over the entire district ; terraces are cut in the rearrangedmaterial of this, bordering the river-valleys, and at greater eleva­tions expanding over the higher parts of the plateau and moun­tains. Some of the wide trough-like valleys of the plateau con­tain a silty material which the author regards as a glacial mud.North of the 54th parallel and west of the Rocky Mountainssimilar evidence of glaciation is obtained. The fjords of BritishOolumbia are extremely glaciated, the marks being generally in con­formity with the local features." He" considers that the mostprobable explanation of the phenomena of the whole region is tosuppose the former existence of a great glacier mass resemblingthe inland ice of Greenland, and that the Glacial period was closedby a general submergence, during which the drifts were depositedand, at its close, the terraces cut."·

In a letter published in Nature, January 27th, 1881, Mr. G. M.Dawson further controverted the general conclusions of ProfessorWhitney, and shows that whilst only a small portion of the highestrange of the mountain has been covered with glaciers, yet therehas been, in this as on the other side of the range, a decidednorthern drift period, distinct from and posterior to the tertiary.I, therefore, conclude that the Rocky Mountains, on both sides,display the same succession of phenomena as has long been provedto have occurred elsewhere, and that the superficial drifts arerecent, that is to say post-tertiary.

* Abstract of Proceedings, March 9th, 1881.