THE GOLD PIJACERS OF PARTS OF -The Future 0.f the Mining In.6ustrj- Page 136 In addition to the stre3111 placers above considered, there are ~ZSQthe auriferou-s deposits in the gravel plains, of vinich that of the Nome tundra is the most e:ci;er?sive, and in the high-bench deposits. The gravel plain stretcking inland from the coast at Nome, usuzlly csl-led the tundra, is The rlchest of this cl~~ssof deposits thus far prospected, but sixilar deposits, some of which arc kno~mto be auriferous, occw in other parts of the peninsula. It will remein for the future to determine what percentage of this type of placers can be profitably eqloited, but in the opinion of the witer it constitutes the :Largest gold reserve of the peninsula. In estinating the gold contents of the grsvel--pl.ain placers values of 25 to 50 cents per cubic yard of pay streak have bee2 adopted as being conservative. As in preview calculations the pay streak has been assumed to be 3 feec thick. The pay stresks of the coastal--plain grzvcls, Imam to conZain con- sidereble gcld, have been assumed to carry 50 cents and the others 25 cents to'the cubic yard. THE GOLD PLACERS OF PARTS OF SEWARD PENINSULA, ALASKA.-- The Future of the Mifiing Indastrx Page 137 Cf the 750 linear miles of gold-bearing creeks, only 172 mi:Les represent creeks vrhich ha,ve produced gola in corn- mercial quantities, but it must be remembered that many have not been carefully prospected and thzt there me probably other creeks not so marked on the accompanying map which will be found to carry gold. MY. Noff'it's computations indicate that those parts of the creeks which have been worked ou't carried values avera.ging proba-bly $500,000 to the mile. Some of the richest creeks have yieldea more than double this but the yield of others is very much below it. THE MILD PLACERS OF PARTS OF SEWARD PENINSULA, ALASKA. , The Future of the Mining Indust= Page L3g A1.l the above facts being taken into consideration, it is believed that an estimate of $250,000,000 to $~25,000,000 for the placer-gold reserves of Seward Peninsula is conservative. Althougk~th.ese speculations may be of interest in showing the posslbi9.iti.e~and proba,ble direction of future growth, the actual estimate of the gold reserve must be regarded as little more than a bold guess. -The Nome Rxion- General Geology d-- Nome Series - -9,tructure Page l3G It has been stated that the Nome series forms a broad ~ync:Linal trough, w:Lth an approximately east-west axis, extending from the coast of Bering Sea to the Kigl~aik Mountzlns. There is, however, ahundant evidence of an earllier deforwation, due to forces acting almost at right angles to those which gave rise to the broad east-west folds and producing other folds much more intense in character and with axes running north to south or from north-northwest to south-couthea.st . Yet, in spite of these defo~aations,itwas found that the bedding of the sediments and the cleavage or schistosity are nearly everywhere the same, although exceptions are lmo~m. -AR.EAL GEOLOGY OF ALASKA Tertiary System Seward Peninsula-- Page 65 Tertiary sediment rocks that were laid down under land conditions have also been identified at a number of goints in Seward Pen:Lnsula - r,a.mely, in the ve.lley of the Sinuk River, in the western part of the peninsula; in the valley of the Kupuk River, in the northern part; and in the valley of the X:oyuk River, ir~the southesstern part. Most of these tracts now ha.ve only a sme.11 extent, but doubtless in the pa.st they were much Z~.rgerand have been reduced through erosion or through being covered an2 rna.sked by later deposits. In all these localities the beds are dominantly composed of sand- stone an6 shale, with some coaly layers. In the locality on the Kugruk River the coal is very thick and ha,s long been mined as a source of' 1oca.I fuel. All the beOs have been somewhat deformed, so that in pleces dips of as much as 70' are by no means unusual. The pa:leontologic evidence as to the age of these rocks is not aaequate for basing a final ccnclusion but it is believed to indicate thst the beds are Xooene and prohebly are in generel correletive with the beds of similar connositi~nand. rela,tlon thst ere so widely dis- tributed through other parie of Alaska md that have b~ usually been refer-e? to as Kenai. MINERAL --RESOURCES OF -ALASKA. 192q -Metallif erous Lodes- in Southerq- Seward Peninsula. Mineralization - .Rock- Openings Page 172 The blaclc slate member of the series is best de- velcped in the Solomon region. It covers a very sna.11 area but is exceptional among the rocks of the seriee in the way in which it hss fissured. It is a dense siliceous, uniform-textured rock which has fractured along clear,-cut lines. The veins of Big Hurrah Creek occur in this formation and are the best defined. and moet regular of the veins known in the region. The contrast between the fracturing qualities of this division of the Norne group and those of the schist af- fords a good explanation why most of the veins ~f Beward Peninsula have proved so irregular and discouraging to prospectors. TIB GOLD PLACERS OF PARTS OF SET<J&RDPENINSULA, ATaASTU. , ---Gold in Bed Rock Distri,bution-. -__I-- of Mineralizqtio; Page 121. The gold placers of Seward Peninsula fall into two broad belts, separatsd by the Kigluaik and Bendeleben mountains. :In the southern belt, at present thz largest producer sf gold, are included the None, Solomon, and Ophir regions and some snallerl mining districts. The Bluestone, Kougarok, and Fair- haven placers lie in the northern zone, The absence of pl-acer gold in intervening regions suggests the 2,bsence of gold from 'the bed rock, but me.y a,lso be explained by the fact that glaciation and other conditions have not been fmorabl-e to the accumulation of auriferous gravels. Within the two belts the placers ars so irregularly distributed as to make it certain that some other cause ]nust have opera.ted in determining their occurrence than the accidents of erosion and deposition. On some creeks there are rich placers, while at near-by localities, where the character of the alluvial deposits is identical, gold may be almost entirely absent. A naturzl inference is that this irregularity is due to the irregularity of the distribution of the golC in bed rock. It has already beer. pointed out that there appears to be a connection between structure and the distribution of the auriferous gravel. This view is borne out by the evi-- dence of the geologic mgps, vrhich indica,te that most of the worlrabl.e ple.cers occu~e.long or close to tihe contacts of :limestone and schists. These conta,cts have in many plzces been exposed to erosion as a resulT of the dona1 uplifts already mentioned. This, however, is not everywhere the case, for some of the limestcne-sckis? contacts are simply the rnzrtgins of lenses of limestone included in the schist. Be the relstion of the limestone to the schist what it ma,y, it t3pnear.s to be esta.blished that the bed-.r~c'xsource of the goLd in most deposfas is traceable to a limestone-schist concact. Ftwthernare, these contacts a?pear to have been Loci of the greatest mineralization, either as impregnated zones or as fissure veins. MINERAL --RESOURCES OF ALASKA, :Lm Lode Developments on Seward --. P.eninsultz -Iron Page 407 A hot spring 2 miles below the location of the claims is said to maintain a uniform flow during surilmer and winter and could possibly be used to generate electric power. Another possible resource is coal. Coal-bearing rocks outcrop on Coal Creek, a tributary of Sinuk River, a short distance below the iron prospects. It is reported that a tunnel driven to prospect the coal cut 17 thin seamo ranging in thickness from 3 to 16 inches. The coal 1% said to be of bituminous grade and of fair quality, but the extent of the coal-bearing rocks is not known. -MINERAL SOURCES , OF ALASKA, . 49.13 Lode Developments of Seward PenJ-nsula. Types of --Gold Lodes Page 399. The auriferiaus quartz veins have further 'been separated into two classes, one in ivhich the gold is associated with the sulphides of iron, arsenic, and antimony or other minerals, and one in which the gold has no mineral association except ~iththe qusrtz. In the sulphide-bearing lodes, whether fissWe veins or disseminated fracture zones, the gold either occurs free in the su1phi.de or inclosing quartz or is presenZ in a state of chemical combination. A division made on this basis is the most important claasLfioation from economic considerations, as the deposits of the two kinds require entirely differen$ plants for the treatment of the ore. Failure on the part of' oyerstors to determine the character of the oYe in depth has c~uusedconsiderab3e loss in the erection of machinery n~tsuitable for treating the ore. The goid-bearing lodes of Seward Peninsula have been charactsri~~edzs a, type of Alsskan deposit peculiar to this region, as it has never been proved that they bear a genetic relation to intrusive rooks, like most of the other gold-lode deposits of Alaska.