V-

DEPARTMENT OF THE INTERIOR FRANKLIN K. LANE, Secretary UNITED STATES GEOLOGICAL SURVEY GEORGE OTIS SMITH, Director PROFESSIONAL PAPER 108 C

A COMPARISON OF PALEOZOIC SECTIONS IN SOUTHERN NEW MEXICO

BY

N. H. DARTON

Published May 29,1917

Shorter contributions to general geology, 1917 (Pages 31-55)

WASHINGTON GOVERNMENT PRINTING OFFICE 1917

DEPARTMENT OF THE INTERIOR FRANKLIN K. LANE, Secretary UNITED STATES GEOLOGICAL SURVEY GEORGE OTIS SMITH, Director

Professional Paper 108 C

A COMPARISON OF PALEOZOIC SECTIONS IN SOUTHERN NEW MEXICO

BY

N. H. DARTON

Published May 29,1917

Shorter contributions to general geology, 1917 (Pages 31-55)

WASHINGTON GOVERNMENT PRINTING OFFICE 1917

CONTENTS.

Page. Page. Introduction...... 31 Silurian system Continued, Cambrian system...... 32 Fusselman limestone Continued. General features...... 32 41 Bliss sandstone...... 32 41 Franklin Mountains...... 32 Caballos Mountains...... 41 Florida Mountains and Cooks Range...... 32 42 Silver City region.... + ...... 32 42 Caballos Mountains.. .j...... 33 42 San Andres Mountains...... 33 42 Sacramento Mountains...... 33 43 Mimbres Mountains...... 33 43 Ordovician system...... 34 44 General features...... 34 44 El Paso limestone...... 34 44 Franklin Mountains...... 34 44 Florida Mountains...... 34 44 Cooks Range...... 34 Florida Mountains ...... 44 Snake Hills...... 35 Silver City...... 44 Victorio Mountains...... qc 44 Klondike Hills...... 35 45 Silver City region...... qc 45 Caballos Mountains...... qc San Andres Mountains...... 45 Lake Valley district...... 35 45 Mimbres Mountains...... qc Age and correlation ...... 46 San Andres Mountains...... 35 46 Sacramento Mountains...... 36 46 Fossils...... q« 47 Age and correlation...... q« 47 Montoya limestone...... q7 Orvnlra "RdTiom 48 General relations...... :...... q7 48 Franklin Mountains...... q7 48 Luna County...... q7 48 Silver City region...... qo 48 Caballos Mountains and adjoining regions. qc 49 Lake Valley...... qc 49 Mimbres Mountains...... qa 50 San Andres Mountains...... qq 50 Sacramento Mountains...... qq Magdalena group ...... 53 Fossils...... qq Cooks Range...... 53 Age and correlation...... 40 Silver City region...... 53 Silurian system...... 41 53 Fusselman limestone...... 41 53 Franklin Mountains and eastward...... 41 Gym limestone ...... 53 Cooks Range...... 41 Hueco limestone...... f ...... 55 Florida Mountains...... 41 Geologic history...... 55 ni ILLUSTRATIONS.

PLATE XIII. Map of part of New Mexico and adjoin­ FIGURE 2. Columnar sections showing atratigraphic ing regions, showing relations of relations of Paleozoic rocks in southern lower Paleozoic rocks...... 32 New Mexico...... 31 XIV. A, Bliss sandstone in Bennett Can­ 3. Section across the Franklin Mountain? yon, 18 miles northeast of Las 3 miles north of El Paso, Tex...... 32 Cruces, N. Mex.; B, West face of 4. Section across Cooks Range at Cooks, Sandia Mountains at Bernalillo, N.Mex...... 35 N. Mex...... 32 5. Section through the Klondike Hills, XV. Views on east side of San Andres Luna County, N. Mex...... 36 Mountains, west of Alamogordo, 6. Section through the Snake Hills, south­ N. Mex.: A, View looking east out west of Deming, N. Mex...... 37 of mouth of Hembrillo Canyon; B, 7. Cross section showing relations of Paleo­ View looking northeast in Good- zoic rocks in the Silver City region, fortune Canyon...... 33 N.Mex...... 38 XVI. A, West face of Caballos Mountains 8. Section across the Caballos Mountains, near Apache Canyon, Sierra County, southwest of Engle, N. Mex...... 39 N. Mex.; B, Paleozoic rocks on 9. Sections across the San Andres Moun­ granite at Capitol Dome, Florida tains, Socorro and Dona Ana counties, Mountains, Luna County, N. Mex.. 34 N. Mex...... 42 XVII. A, Sierra Cuchillo west of Palomas 10. Section through the Lake Valley mining- Springs, N. Mex.; B, Fault in lime­ district, Sierra County, N. Mex...... 44 stone at Palomas Gap, Caballos 11. Columnar sections showing stratigraphic Mountains, Sierra County, N. Mex.. 35 variations in lower Paleozoic rocks in XVIII. A, Limestones from Ordovician to the San Andres Mountains, Dona Ana Pennsylvanian on granite, Sheep and Socorro counties,N.Mex...... 45 Mountain, San Andres Mountains, 12. Section from the Mimbres Mountainr Socorro County, N. Mex.; B, East eastward through Kingston and Hilla- face of San Andres Mountains at boro. N. Mex...... 48 Rhodes Canyon, Socorro County, 13. Section of the west front of the Sacra­ N.Mex...... 36 mento Mountains, 12 miles southeast XIX. A, North side of entrance to Alamo of Alamogordo, N. Mex...... 50 Canyon, 3 miles southeast of Alamo­ 14. Section along western slope of the gordo, N. Mex.; B, Kelly limestone Sacramento Mountains east of Alamo­ at Graphic mine, near Magdalena, gordo, N. Mex., from La Luz Canyor N.Mex...... 37 to Grapevine Canyon...... 51 XX. View looking southeast along weat 15. Section across the southern part of the front of Sacramento Mountains Florida Mountains, Luna County, from Alamogordo, Otero County, N.Mex...... 54 N.Mex...... 50 XXI. View along west front of Sacramento Mountains at Agua Chiquita Can­ yon, Otero County, N. Mex...... 51 COS I.:; *-JIJ NVS Mxr»o*iD j,siocno3") HO

A COMPARISON OF PALEOZOIC SECTIONS IN SOUTHERN NEW MEXICO.

By N. H. DABTON.

INTRODUCTION. in publications by Gordon and Graton, Lee, In studying the geology oi different parts Herrick, and others. of southern New Mexico the writer has ob­ It has been known for some time that in tained many new data on the distribution southern New Mexico there are representa­ and relations of the sedimentary rocks. The tives of portions of later Cambrian, Ordovi- stratigraphy of the Pennsylvanian series was cian, Silurian, Devonian, earlier Mississippian, investigated in detail, and in Luna County all and Pennsylvanian time, and that the lower the formations were studied.1 A recently formations thin out to the north, so that in

Frankli n F lorid 3 ( :ooks Silver C aballc s Lake K hgst 3n- SanAnd res Sac rame nto Mts MtS. F City Mts. Valley H llsbo TO Mts Mts.

TERTIARY *~t**tf; TERTIARY _i— 1_ agglom­ jK Red beds \ erate erate 2,000 (Abo) 10 soo/ o 1 !_!_ FCoJpfSab' £00+ a i 1 Colorado 1 //|r l,000± 1,800 + Hueco 300 "-- o 1 1 ' $ ^ m Gap ~"~ — -i?~ Red beds . cc • ' Gym \ S 1 1 i i 1 1 i i / . 1 1 i i / I,IOO± 1 1 Gym / limestone i i Fierro i / * — i— i- / 600 \\ \ -U-L- 800 \ \ • 650 i ' i ' / •z. 1,200,' ^ \ 1 1 i i i i •> Lake i ' i 1 CL i i _J_ L _• Valley --t^r i i 300 JD;50 •i i fe---_ i i :75^ to _,- ^r- i i 500 ,' i i 163-—- - —— JTjf i i 300 i— r i i i i . 50 IS ^-aoo — 7 —— —— - i i = !<=!= 200 -~? 350 ZOO ORDOVICIANSIU.CAMBRIANORDOVICIAN Montoya 300 250 350 / 1 1 to 350 150 -i- i i 400 j— i — n75--~ 200 tt &£ U^- 300 ^&? 300 600 to i^ PRE-LATEEARLYLATE 800 900- 400 v s' 1,000+ i El Paso -100+—— ^s / 20ti\ / / 180' . L _., L, 200,--^ "Oto f Bliss 2OO ____- Scale 500 0 5CX3 1 000 Feet Granite,etc. P i 'S-^T? mf Mississippian fossi s m Magdalena fossils

FIGURE 2. Columnar sections showing stratigraphic relations of Paleozoic rocks in southern New Mexico. published folio 2 gives many new facts for the central New Mexico the strata of the Penn­ stratigraphy of the Silver City region, some of sylvanian series lie directly on the pre-Cam- which are utilized in the present paper. Rich­ brian crystalline rocks, as shown in Plate ardson's work in the El Paso region 3 estab­ XIV, B. There are also numerous irregulari­ lished the succession in the southeastern part ties in the overlap relations of the formations. of New Mexico. There are also many details The broader features of the stratigraphy of this region are here presented. The principal 1 Darton, N. H., Geology and underground waters of Luna County, N. Mex.: U. S. Geol. Survey Bull. 618, 188 pp., 13 pi., 1916. Paleozoic formations in southern New Mexico- 2 Paige, Sidney, U. S. Geol. Survey Geol. Atlas, Silver City folio (No. are shown in the columnar sections (fig. 2), 199), 1916. s Richardson, G. B., U. S. Geol. Survey Geol. Atlas, El Paso folio and some conditions of the distribution of the (No. 166), 1909. formations are indicated on the map (PI. XIII). 31 32 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1917.

CAMBRIAN SYSTEM. beds comprise Lingulepis acuminata, Obolus matinalis ?, and fragments of Lingulella. Some GENERAL FEATURES. relations of the Bliss sandstone in the Frank­ The presence of Cambrian strata in New lin Mountains are shown in figure 3. Mexico was announced by Gordon and Gra­ Florida Mountains and Cooks Range.—In ton 1 in 1906, on the evidence afforded by the Luna County the Bliss sandstone is similar in discovery of Otolus stoneanus in sandstones on character, thickness, and relations to the forma­ the west side of the Caballos Mountains near tion in its type locality. It crops out in the Shandon. In 1910 the name " Shandon quartz- Florida Mountains and Cooks Range, as well ite" 2 was given to the beds at this place, as in several outliers, everywhere lying with and they were tentatively correlated with the strong unconformity on granite, as shown in Bliss sandstone of the Franklin Mountains, Plate XVI, B (p. 34), and grading upward into near El Paso, Tex., defined by Richardson 3 in the El Paso limestone. Gray to brown sand­ 1904. Sandstones and other rocks of Cambrian stone prevails; part of it is quartzitic, but the age occur at many places in Arizona, where upper beds are slabby and have intercalations apparently they underlie wide areas. The of sandy and limy shale. The formation con­ name Bliss sandstone has been adopted for tains much glauconite. Its average thickness

BoU

FIGUKE 3. Section across the Franklin Mountains 3 miles north of El Paso, Tex. (After Richardson.) gr, Granite; b, Bliss sandstone; e, El Paso limestone; m, Montoya limestone; f, Fusselman limestone. southern New Mexico because of its priority is 150 feet, but locally it is much thinner. No in the El Paso region. It replaces the name fossils were found in these areas. "Shandon quartzite." Silver City region.—In the Silver City region the Bliss sandstone consists of quartzite and BLISS SANDSTONE. limy sandstone containing some glauconite Franklin Mountains.—In its type locality, throughout. The thickness averages 180 feet, at the east base of the Franklin Mountains, the but varies somewhat. At most places the Bliss sandstone consists of small grains of basal member is quartzite, which grades up­ quartz embedded in a matrix of sericite and ward as a rule into fine-grained greenish sand­ kaolin. The basal beds are mostly quartzitic stone but locally into soft ferruginous sand­ and locally conglomeratic, and the higher beds stone, and here and there the greater part of are softer and finer grained. The prevailing the formation is quartzite. At the top there color is brown, but some portions have lighter is generally a thin quartzite or glauconitic tints. A thickness of 300 feet is attained in sandstone, grading upward into limy sandstone places, but locally the formation thins out and that appears to merge with the overlying El overlying limestones rest on the pre-Cambrian Paso limestone. A typical section given by rocks. It appears to grade upward into the Paige 4 is as follows: El Paso limestone. Annelid borings are abun­ Section of Bliss sandstone 7 miles northwest of Silver City, dant, and a few brachiopods in the lower N. Mex. Feet. i Gordon, C. H., and Graton, L. C., Lower Paleozoic formations in Sandstone, coarse, glauconitic...... 12 New Mexico: Am. Jour. Sci., 4th ser., vol. 21, p. 392, 1906. See also Limestone, sandy; thin, wavy bedding; fucoid Lindgren, Waldemar, Graton, L. C., and Gordon, C. H., The ore de­ posits of New Mexico: U. S. Geol. Survey Prof. Paper 68, p. 225,1910. markings...... 47 1 Lindgren, Waldemar, Graton, L. C., and Gordon, C. H., op cit., Quartzite, coarse, slightly cross-bedded...... 17 p. 225. Sandstone, limy; thin, wavy bedding; fucoids?.... 57 * Richardson, G. B., Report of a reconnaissance in trans-Peeos Texas north of the Texas & Pacific Railway: Texas Univ. Mineral Survey « Paige, Sidney, Geol. Survey Geol. Atlas, Silver City folio (No. 199), Bull. 9, p. 27,1904. 1916. U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 108 PLATE XIII

1O5° 1O7 1O6

Outcrop of lower Paleozoic rocks (Cambrian to Ordovitian; overlain in most raojcesby Silurian and Devonian and locally by lower Mississippian)

Contact of Cambrian on granite

Contact of Mississippian on granite elen T O R

Contact of Pennsylvanian on granite SljERRA MONTOSA Limit of Mississippian (Approximate)

NEW MEXICO C OC HIS E

108° 106° 109 1O7

10 0 10 20 30 40 50 60 70 80 90 100 Miles

MAP OF PART OF NEW MEXICO AND ADJOINING REGIONS, SHOWING RELATIONS OF LOWER PALEZOIC ROCKS.

U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 108 PLATE XIV

A. BLISS SANDSTONE IN BENNETT CANYON, 18 MILES NORTHEAST OF LAS CRUCES, N. MEX. B, Contact of Bliss sandstone and El Paso limestone.

B. WEST FACE OF SANDIA MOUNTAINS AT BERNALILLO, N. MEX. a, Sandia formation on granite, etc. U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 108 PLATE XV

A. VIEW LOOKING EAST OUT OF MOUTH OF HEMBRILLO CANYON. f, Fusselman limestone; m, Montoya limestone; e, El Paso limestone; b, Bliss sandstone; gr, granite.

B. VIEW LOOKING NORTHEAST IN GOODFORTUNE CANYON. mgr, Microgranite; mg, limestone of Magdalenagroup; Iv, Lake Valley limestone; p, Percha shale; m, Mon­ toya limestone; e, El Paso limestone; b, Bliss limestone; gr, granite.

VIEWS ON EAST SIDE OF SAN ANDRES MOUNTAINS, WEST OF ALAMOGORDO. N. MEX. COMPARISON OF PALEOZOIC SECTIONS IN SOUTHERN NEW MEXICO. 33

Feet. Quartzite, massive, cross-bedded, ferruginous, glau- miles northeast of Las Cruces, where it is 125 conitic; pebbly streaks...... 17 feet thick and lies between granite and the El Sandstone, soft, glauconitic...... 13 Paso limestone. This exposure is shown in Quartzite, massive, coarse (on granite)...... 15 Plate XIV, A. The Bliss is 60 feet thick 2 miles 178 northeast of Organ, where it is cut off by igne­ The area of outcrop of the formation is small. ous rocks. At this locality the rocks are It appears along the west slope of the ridge north­ sandstone, mostly hard, and many layers west of Silver City and on some outlying ridges contain considerable glauconite. In San An­ and in a small exposure at the west end of Lone dres Canyon the formation comprises 110 Mountain, 6 miles southeast of Silver City. feet of beds, consisting Of a lower member of The beds near the base yielded abundant speci­ gray quartzite, mostly massive; a medial mem­ mens of BiUingsella coloradoensis, an Upper ber of brown sandstone, partly slabby; and Cambrian fossil. an upper slabby member that apparently Caballos .Mountains.—The Bliss sandstone in merges with the base of the El Paso limestone. the Caballos Mountains has been described by In the central part of the range, at Deadman Gordon and Graton1 and by Lee.2 As ex­ and Hembrillo canyons, the thickness is from plained above, the beds at this place were 30 to 40 feet. (See PL XV.) In Sulphur called "Shandon quartzite." They lie on a Canyon it consists of 25 feet of brown sand­ smooth plane on granite, which is exposed to a stone, conglomeratic at the base, grading up­ height of about 1,000 feet above the Rio Grande ward into 30 feet of thin, slabby softer sand­ on the west slope of the range, as shown in stone, in part glauconitic, which appears to figure 8 (p. 39) and Plate XVI, A (p. 34). grade into slabby, finer sandstone, and this in Gordon and Graton described a thin basal turn into an impure buff slabby limestone that member of dark quartzite, absent in places; is certainly the El Paso. In Rhodes Canyon white quartzite 4 to 5 feet thick; and an upper the sandstone that separates the El Paso beds member, 40 feet thick, of dark-brown and green from the granite is 6 feet thick, and this thin sandy shales and thin-bedded quartzite carry­ deposit extends northward, as shown in Plates ing Obolus. The beds recorded by Lee in a XV, B, and XVIII, A (p. 36). section 3 miles north of Shandon consist of a Sacramento Mountains.—In the small ex­ basal quartzite 10 feet thick, in places con­ posure of the base of the sedimentary rocks glomeratic, grading upward into 90 feet of just south of the mouth of Agua Chiquita Can­ dark-green shale. The shale yielded Obolus yon, in the Sacramento Mountains, the El Paso (Westonia) stoneanus, Obolus sinoef, Eoorfhis limestone is separated from a dark granite by desmopleura, and Lingulella acutangulata?, de­ a few feet of hard sandstone, which is presum­ termined by C. D. Walcott and regarded as ably Bliss. It is not especially characteristic, Upper Cambrian. A similar section was ob­ however, and yielded no fossils, so that the served by Lee in Cerro Cuchillo, near Palomas correlation can be only tentative. Spring. (See PL XVII, A, p. 35.) In both Mimbres Mountains.—According to Gor­ places the overlying limestone is the El Paso. don,3 the limestone in the east slope of Mimbres Lee states that the basal quartzite thickens to Mountains is separated from the granite by 300 feet 8 miles south of Shandon. quartzite, which undoubtedly represents the San Andres Mountains.—The Bliss sandstone Bliss sandstone. (See fig. 10, p. 44.) Expo­ crops out continuously along the east slope of sures on Carbonate Creek show 75 feet of dark- the San Andres Mountains, but it becomes red quartzite, which includes a 3-foot bed of very thin in the north end of the range. (See shale near the middle and rests on an irregular figs. 9, p. 42, and 11, p. 45.) The formation is a surface of red granite. In most of the slopes conspicuous feature in Bennett Canyon, 18 of these mountains the basal formations of the sedimentary series are hidden by younger i Am. Jour. Sci., 4th ser., vol. 21, pp. 391-392,1906; TJ. S. Geol. Survey Prof. Paper 68, pp. 225-226,1910. igneous rocks, which cap the range. 8 Lee, W. T., Notes on the lower Paleozoic rocks of central New Mexico: Am. Jour. Sci., 4th ser., vol. 26, pp. 180-181,1908. »U. S. Geol. Survey Prof. Paper 68, pp. 268, 269,1910. 34 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1917. ORDOVICIAN SYSTEM. everywhere there is a sharp break. The upper GENERAL FEATURES. member of the Montoya invariably consists of alternating layers of limestone and chert car­ Ordovician rocks were first discovered in the rying abundant Richmond fossils. Southwest by G. G. Shumard in 1856,1 who found fossils now known to be characteristic of El PASO LIMESTONE. the Ordovician in the Franklin Kange at El Franklin Mountains.—The El Paso limestone Paso. Some years later the geologists of the was separated from other Ordovician strata Wheeler Survey 2 found similar fossils at sev­ in the Franklin Mountains north of El eral localities, including the vicinity of Silver Paso by Richardson.6 In the type locality City, N. Mex. the formation consists of about 1,000 feet of Gordon and Graton 3 found other fossilifer- gray limestone mostly massive but in part ous localities in southern New Mexico in 1905. slabby. The lower 100 feet contains some The beds of Ordovician age which they de­ sand and weathers brown. Where it is in con­ scribe are about 750 feet thick, and in 1910 tact with pre-Cambrian rocks the basal mem­ these beds, together with a Silurian limestone ber 20 feet thick consists of round pebbles of that overlies them in places, were designated porphyry in a limy matrix. In the middle of the "Mimbres limestone."4 All these limestones the formation occur thin connected nodules of are well represented in the Franklin Mountains brown chert in streaks parallel to the bedding, north of El Paso, where Richardson 5 subdi­ but this feature, characteristic here, was not vided them into the El Paso and Montoya observed in other regions. Magnesia is a limestones, of Ordovician age, and the Fussel- general constituent in variable amount. The man limestone, of Silurian age. As these principal outcrop is along the eastern flank of formations are separable throughout southern the Franklin Mountains, where the relations New Mexico, the name "Mimbres limestone" are those shown in figure 3 (p. 32). Distinctive is no longer useful. Throughout the region Lower Ordovician fossils were found in the the middle part of the Ordovician and the lower formation at many places. part of the Silurian appear to be absent. Florida Mountains.—The El Paso limestone The Ordovician succession in southern New is extensively exposed in the south-central Mexico shows everywhere uniform and very part of the Florida Mountains and also on the marked characteristic features. They are won­ northwestern slope of that range a short dis­ derfully distinct at the many widely scattered tance southwest of Deming. (See PI. XVI, B.) exposures examined by the writer, from the At the latter place the thickness is about 800 Franklin Mountains west to Silver City, and feet and the lower 140 feet is darker and more to the north in Cooks Range, Lake Valley, and massive than in other outcrops. The greater the San Andres, Caballos, and Sacramento mountains. The El Paso limestone, at the base part of the formation consists of light-gray of the section, is in most places of unmistakable slabby dolomitic limestone with pale reddish- character, its conspicuous features being thin brown blotches over the bedding planes. bedding, a light color on weathering, and There is very little chert. The upward grada­ brownish-buff reticulations on the bedding tion from the Bliss sandstone is well marked, planes, caused by irregular layers of an iron- and the change to the overlying Montoya lime­ silica deposit probably due to a seaweed. This stone is abrupt. The structural relations in formation is overlain by dark massive lime­ the southern part of the range are shown in stone at the base of the Montoya; locally a thin figure 15 (p. 54). sandstone separates the two limestones, and Cooks Range.—At the north end of Cooks Range and in Fluorite Ridge, at its south end, 1 Shumard, G. G., A partial report on the geology of western Texas, the El Paso is well exhibited. The northern p. 103, Austin, 1886. 2 TJ. S. Geog. and Geol. Expl. W. 100th Mer. Rept., vol. 3, pp. 515-517, exposures show 600 feet of beds between the 1875. Bliss sandstone and the sandstone member at « Am. Jour. Sci., 4th ser., vol. 21, pp. 392-393, 1906. < TJ. S. Geol. Survey Prof. Paper 68, p. 226,1910. the base of the Montoya. The relations near 6 Richardson, G. B., TJ. S. Geol. Survey Geol. Atlas, El Paso folio (No. 166), 1909. e TJ. S. Geol. Survey Geol. Atlas, El Paso folio (No. 166), 1909. U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 108 PLATE XVI

A. WEST FACE OF CABALLOS MOUNTAINS NEAR APACHE CANYON, SIERRA COUNTY, N. MEX. Looking northeast, gr, Granite; b, Bliss sandstone.

JB. PALEOZOIC ROCKS ON GRANITE AT CAPITOL DOME, FLORIDA MOUNTAINS, LUNA COUNTY, N. MEX. Looking northeast, ag, Agglomerate; m, Montoya limestone; e, El Paso limestone; gr, granite. U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 108 PLATE XVII

A SIERRA CUCHILLO WEST OF PALOMAS SPRINGS, N. MEX. Looking northwest. Granite, Bliss sandstone, Ordovician and Pennsylvanian limestones.

B. FAULT IN LIMESTONE AT PALOMAS GAP, CABALLOS MOUNTAINS, SIERRA COUNTY, N. MEX. Looking north. COMPARISON OF PALEOZOIC SECTIONS IN SOUTHERN NEW MEXICO. 35

Cooks are shown in figure 4. In Fluorite nearly the same distribution as the Bliss sand­ Ridge, 12 miles north of Deming, the beds are stone in Lone Mountain in the Silver City so crushed and faulted that only about 400 Range, northwest of Silver City, and in an feet of the El Paso limestone appears. area north of Bear Mountain. Snake Hills.—The east end of the Snake Hills, Caballos Mountains.—The El Paso lime­ a small range rising out of the desert a few stone is a prominent feature in the great miles southwest of Deming, consists of El section along the west front of Caballos Paso limestone showing distinctive features Mountains, where it has the relations shown and fossils. The base of the formation is not in figure 8 (p. 39) and Plate XVI, A. The exposed, but to the west, as shown in figure 6 Bliss sandstone grades upward into the El (p. 37), its top passes under the Montoya Paso, and above it are typical cherty beds of limestone with marked unconformity. the Montoya limestone. It constitutes 300 or Victorio Mountains.—The knob constituting 400 feet of the lower part of the limestone the northeastern member of the Victorio cliffs, and the rocks present the same char­ Mountains presents extensive exposures of El acteristics that are seen in the Franklin Paso limestone, 600 to 700 feet thick at least, Mountains and Luna County. However, Lee * dipping south toward a mass of Montoya lime­ notes a section 8 miles south of Shandon in stone which constitutes much of Mine Hill. which it consists of 200 feet of cherty lime­ The El Paso beds present the usual slabby stone, overlain unconformably by 500 feet of character, weather to a light -color, and show cherty limestone (Montoya and later).

Horizontal scale Vertical scale 4.00OFEET

FIGTTBE 4. Section across Cooks Range at Cooks, N. Mex. gr, Granite; b, Bliss sandstone; e, El Paso limestone; m, Montoya limestone; f, Fusselman limestone; p, Percha shale; Iv, Lake Valley limestone; g, Gym limestone; 1, Lobo formation; s, Sarten sandstone (Creta­ ceous); ag, agglomerate. abundant pale-brown reticulations on the bed­ acteristic fossils were found by Lee in both ding planes. formations. Klondike Hills.—The Klondike Hills, 12 LaTce Valley district.—The lower 150 feet miles south of the Victorio Mountains, consist of the limestone in Quartzite Ridge, on the mainly of the El Paso and Montoya lime­ west side of the Lake Valley mining district, stones, the former mostly in the western part is made up of El Paso beds. On the east of the ridge as shown in figure 5. At one place these beds are overlain by 20 feet of hard the underlying Bliss sandstone is exposed. sandstone at the base of the Montoya lime­ The thickness is about 650 feet and all the stone, and on the west they are cut off by usual features are presented. At the top there igneous rocks. The relations are shown in is an unconformable overlap of sandy beds at figure 10 (p. 44). The rocks are the highly the base of the Montoya limestone, but the characteristic slabby limestone, weathering to attitude of both formations is practically the a light color and having most of the bedding same. planes stained with brownish reticulations. Silver City region.—In the vicinity of Silver Mimbres Mountains.—Gordon and Graton 2 City the El Paso limestone is mostly gray or report an extensive section of Ordovician grayish blue and in part magnesian. It ap­ rocks in the Mimbres Mountains near Kingston, i pears to grade upward from the Bliss sandstone, At this place the lower division doubtless ' the lowermost 100 feet becoming progressively represents the El Paso limestone, but it is less sandy. The lower and middle parts are mostly a blue and white marble, and the dis­ slabby, and the slabs have the characteristic tinctive fossils were not found. On Carbonate mottled surface seen in other areas. In the Creek the basal limestone is exposed in con­ upper part the formation is more massive and tact with sandstone of Cambrian age (Bliss). contains considerable chert. The total thick­ 1 Am. Jour. Sci., 4th ser., vol. 26, p. 180,1908. ness is about 900 feet. The formation has 2 Idem, vol. 21, p. 392,1906. 76787° 17 2 36 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1917.

San Andres Mountains.—The El Paso lime­ beds are more massive than at most other stone extends continuously along the east face localities. of the San Andres Mountains, from the igneous Fossils.—Fossils occur in the medial and contact near Organ to the north end of the upper beds of the El Paso limestone at all range. Its relations are shown in figures 9 localities, but they are not numerous either (p. 42) and 11 (p. 45). (See also Pis. XV and individually or in species. A small coiled shell, XVIII, -B.) Its thickness is about 300 feet at Ophileta, is by far the most common form. the south but gradually diminishes northward Richardson 1 found the fauna very meager in from San Andres Canyon to 160 feet on Lost- the Franklin Mountains but collected Ophileta man Canyon, 125 feet at Rhodes Canyon, and and other gastropods, and also cephalopods 80 feet in Lava Gap. In Sulphur Canyon, related to Piloceras and Cameroceras. Higher which is nearly due west of Tularosa, it is 160 beds near Deming have yielded a form re­ feet. The limestone lies on or grades upward sembling DalmaneTla pogonipensis, Stropho- from the Bliss sandstone and has characteristic mena near S. nemea, Hormotoma sp., and slabby structure with the slabs weathering Trochonema. In the Silver City region the light gray and having surfaces mottled with fossils collected by Paige 2 were Calafhium reticulations of brownish-buff markings, prob­ anstedi, DalmaneTla cf. D. wempeli, Proto- ably due to a seaweed. Locally the medial warfhia cf. P. rossi, BucaneUa nana?, LopTio- beds are massive and less distinctive in appear­ spira sp., RapJiistoma trohiscum?, Eccyliopterus ance. Fossils were found at many places. sp., Maclurea cf. M. oceana, Holopea sp., The relations 18 mil^es northeast of Las Cruces Piloceras cf. P. wortheni, Cameroceras, and the

Horizontal scale Vertical scale 9 i , , ippo FEET

FIGURE 5. Section through the Klondike Hills, Luna County, N. Mex. gr, Granite; b, Bliss sandstone; e, El Paso limestone; m, Montoya limestone with sandstone (s) at base; r, rhyolite. and in Lava Gap are shown in figure 9 (p. 42). usual Ophileta. In the Caballos Mountain The formation is conspicuous in Rhodes section Lee 3 collected Ophileta cf. 0. com- Canyon, a few miles south of Salinas Peak planata and Hormotoma cf. H. artemesia. In (see PI. XVIII, B), in about latitude 33° 10', the exposure in Bennett Canyon in the San where it is separated from the granite by only Andres Mountains, 15 miles northeast of Las 6 feet of sandstone, and this relation continues Cruces, were obtained Polygyrata rotuliformis? to the north er^d of the range. and an indeterminable cystid. In the canyon Sacramento Mountains.—The basal limestone 3 miles south of San Andres Peak were col­ in the west front of the Sacramento Moun­ lected Calathium cf. C. anstedi, Polygyrata tains from Alamo Canyon to a point near trohiscus, and Piloceras sp. In San Andres Grapevine Canyon is typical El Paso, show­ Canyon Calathium cf. C. anstedi was found and ing all the features distinctive in other areas, this distinctive fossil was observed throughout including fossils. The relations are shown in the exposures in the San Andres Range. From figures 13 (p. 50) and 14 (p. 51). The thick­ the cliff in Alamo Canyon, in the Sacramento ness is 250 feet, but except in a small area near Mountains, were collected Calathium cf. C. the mouth of Agua Chiquita Canyon the basal anstedi and DalmaneTla pogonipensis. beds are covered by talus. In Alamo Canyon Age and correlation.—The fossils in the El 125 feet of the El Paso is well exposed in the Paso limestone are regarded by Ulrich and cliff on the north side of the creek, capped by Kirk as Lower Ordovician, representing late thin sandstone and dark massive limestone at Beekmantown time. It is possible that in the base of Montoya, as shown in Plate XIX, A some areas strata of early Chazy age have been (p. 37). At Dog Canyon 200 feet is exposed. included with the El Paso. On this basis the The rocks are slabby limestones, weathering 1 U. S. Geol. Survey Geol. Atlas, El Paso folio (No. 166), p. 4,1909. to a light tint, and in part the bedding planes 2 Idem, Silver City folio (No. 199), p. 4, 1916. show brownish-buff reticulations. The medial « Am. Jour. Sci., 4th ser., vol. 26, p. 180,1908. U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 108 PLATE XVIII

A. LIMESTONES FROM ORDOVICIAN TO PENNSYLVANIAN ON GRANITE, SHEEP MOUNTAIN, SAN ANDRES MOUNTAINS, SOCORRO COUNTY, N. MEX. Looking south. Iv, Lake Valley limestone; p, Percha shale; m, Montoya limestone; e, El Paso limestone;gr, granite.

B. EAST FACE OF SAN ANDRES MOUNTAINS AT RHODES CANYON, SOCORRO COUNTY, N. MEX. p, Percha shale; m, Montoya limestone; e, El Paso limestone on Bliss sandstone; gr, granite. U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 108 PLATE XIX

A. NORTH SIDE OF ENTRANCE TO ALAMO CANYON, 3 MILES SOUTHEAST OF ALAMOGORDO, N. MEX. mg, Limestone of Magdalena group; c, cherty member of Montoya; f, Fusselman limestone; m, dark massive member of Montoya; e, El Paso limestone.

B. KELLY LIMESTONE AT GRAPHIC MINE, NEAR MAGDALENA, N. MEX. COMPARISON OF PALEOZOIC SECTIONS IN SOUTHERN NEW MEXICO. 37 limestone has been correlated by Richardson l fossils throughout. The lower 100 feet is with part of the Longfellow limestone in the dark colored; the upper beds range from very Clifton district, Ariz., and the upper 1,000 feet light to dark gray and include layers of chert. or more of the Arbuckle limestone in the The rocks contain considerable magnesium Wichita Mountains, Okla. carbonate. They crop out along the east slope Although the El Paso sediments appear to of the Franklin Mountains and also in a narrow grade downward into the Bliss sandstone, there band in the Hueco Mountains, 9 miles south­ is no evidence that the lowest part of the El east of Hueco Tanks. Paso limestone is latest Cambrian or transi­ Luna County. The Montoya limestone is tional from Cambrian to Ordovician. No well defined in the Florida Mountains, Cooks fossils were found in these lower beds. Range, and some outlying ridges as far west as the Victorio Mountains and Klondike Hills. MONTOYA LIMESTONE. In all these areas the formation consists of light- General relations.—The Montoya limestone, gray slabby limestone with highly fossiliferous of Richmond age, underlies the greater part of layers, a large amount of chert, and at the southern New Mexico as far north as latitude bottom a dark massive limestone or sandstone. 33°; possibly it extends some distance farther Chert is a characteristic feature and gives north under overlapping beds. It lies every­ prominence to the outcrops. It occurs mostly where on the El Paso limestone without notice­ in thin beds alternating with thin layers of able discordance of dips or strongly marked limestone, and such beds in greater part con­ unconformity, although there is a hiatus at the stitute two thick members, each of which is contact representing much of later Ordovician bordered on both sides by beds of purer lime-

Honzontal scale Vertical scale O I.OOO FEET

FIGUKE 6. Section through the Snake Hills, southwest of Deming, N. Mex. e, El Paso limestone; d, dark sandy limestone at base of Montoya; b, cherty members in Montoya limestone; c, massive dark-gray limestone; a, limestone with chert in large bodies high in Montoya limestone. time. In nearly all parts of the area the lime­ stone. The average thickness of the formation stone is overlain by the Fusselman limestone, is 300 feet. the beds of which have the same attitude as In places it is difficult to separate the Mon­ those of the Montoya. toya from the overlying Fusselman, but in the Franklin Mountains.—The fossils found near region north of Cooks Peak there is an abrupt El Paso by G. G. Shumard 2 in 1856 were in change. Here the top member consists of 60 the Montoya limestone. In 1903 Richardson 3 feet of light-colored slabby limestone with a studied the Franklin Mountains, and although very fossiliferous 6-foot member at its base. in his first publication he included in the El This is underlain by 150 feet of limestone con­ Paso limestone all the strata containing Ordo­ taining numerous cherty layers. The basal vician fossils, in a later publication 4 he sepa­ member, 40 feet thick, is a dark-colored mas­ rated as Montoya the beds carrying a Rich­ sive limy sandstone. The total thickness is mond fauna. At one time it was thought that 250 feet. In the Snake Hills, a few miles beds of Galena age were also included in the southwest of Deming, the greater part of the Montoya, but on further study the fossils were formation, 300 feet in all, is exposed. It lies found to be Richmond. on the El Paso limestone, and the relations are In these mountains the Montoya formation shown in figure 6. At the base is dark massive consists of 250 feet of beds carrying Richmond limestone; next very cherty limestone with alternating layers of purer limestone; 30 feet i U. S. Geol. Survey Geol. Atlas, El Paso folio (No. 166), p. 4,1909. a Shumard, G. G., A partial report on the geology of western Texas, of dark-gray sandy limestone grading upward pp. 46,103, Austin, 1886. into purer, partly massive limestone that s Richardson, G. B., Report of a reconnaissance in trans-Pecos Texas, north of the Tesas & Pacific Railway: Texas Univ. Mineral Survey weathers to an olive tint; then a 60-foot mem­ Bull. 9, .p. 29,1904. ber of alternating layers of chert and limestone, * Richardson, G. B., Paleozoic formations in trans-Pecos Texas: Am. Jour. Sci., 4th ser., vol. 25, pp. 478-479,1908. with fossils; and at the top a thick mass of 38 SHOETEE CONTBIBUTIOlSrS TO GENEBAL GEOLOGY, 1917. highly cherty rock at the crest of the ridge. cliff yielded distinctive fossils. Between this In the Klondike Hills (see fig. 5, p. 36) the cherty member and the limestone containing basal member is a dark-gray sandstone, 6 to 8 Pennsylvanian fossils is 500 feet of limestone feet thick, lying on the slightly irregular sur­ whose age was not determined. Lee 2 also face of the El Paso limestone. It is overlain reports outcrops of the cherty limestone in the by 30 to 40 feet of dark massive sandy lime­ Sierra Cuchillo, near Palomas Springs, west of stone, capped as in other areas by a succession the Rio Grande (see PI. XVII, A), and in the including two or three thick cherty members north slopes of Robledo Mountain, 15 miles with limestone layers that contain many south of Rincon, but the fossils collected at the fossils, listed on page 40. latter locality appear more probably to be Silver City region.—The first observers of the Fusselman. Montoya limestone in southwestern New Lee 2 reports that the cherty limestone carry­ Mexico were Howell and Gilbert/ who in ing distinctive Montoya fossils is exposed in the 1873 collected "Cincinnati" fossils from lime­ south end of the Caballos Mountains, 8 miles stones near Silver City and in the Santa Rita south of Shandon, but the rocks are so faulted Range. and crushed that it is difficult to make a sec­ In the Silver City area the M'ontoya lime­ tion. Below these cherty beds is limestone con­ stone shows its characteristic features and has taining El Paso fossils. In exposures along the a thickness of about 300 feet. Its relations in same line of outcrop, about 6 miles west of the ridge west of Silver City are shown in Rincon, 300 feet of cherty limestone exposed at

NW. Treasure Mtn

FIGURE 7. Cross section sh'owing relations of Paleozoic rocks in the Silver City region, N. Mex. (After iPaige.) gr, Granite, etc.; b, Bliss sandstone; e, El Paso limestone; m, Montoya limestone; f, Fusselman limestone; p, Percha shale; fr, Fierro limestone; K and Kc, sandstone and shales of Cretaceous age. figure 7. Although most of the formation is the foot of the cliffs yielded a number of limestone, it contains a large amount of chert, Montoya fossils. Apparently here, as else­ mainly in thin beds interlaminated with the where, the Montoya lies directly on the El limestone. One member of this character, 80 Paso limestone, no intermediate Ordovician feet thick, begins about 40 feet above the top rocks being present. of the El Paso limestone, from which it is Lake Valley.—Lying on the El Paso lime­ separated by magnesian limestone. The base stone in the west front of Quartzite Ridge, west is not distinct. Above the thick chert mem­ of Lake Valley, is 20 feet of gray hard sand­ bers are alternating thin beds of smooth stone, above which is 25 feet or more of cherty whitish limestone and massive beds of blue and brecciated limestone that doubtless repre­ limestone with cherty layers at intervals. sents the Montoya. No fossils were found here. Fossils of the Richmond fauna are abundant, The relations are shown in figure 10 (p. 44). especially in two layers, one near the base and Next above is 80 feet of compact limestone that the other near the top of the formation. weathers to a very light color and is similar to Caballos Mountains and adjoining regions.— beds which are tentatively included in the In the Caballos Mountains, southwest of Engle, Fusselman in other uplifts. Apparently it the Montoya limestone is extensively exposed. does not contain fossils. Lee 2 has given many details of its features, Mimbres Mountains.—According to Gordon with a list of fossils determined by Ulrich. In and Graton,3 the Ordovician limestones out­ a section 3 miles north of Shandon, shown in crop at intervals along the east slopes of the figure 8 and Plate XVI, A, the cherty lime­ Mimbres Mountains from the vicinity of stone near the top of the first great limestone Kingston to and beyond Hermosa. From Hillsboro southward the upper siliceous beds, 1 U. S. Geog. and Geol. Expl. 100th Mer. Kept., vol. 3, pp. 515-517,1875. 2 Am. Jour. Sci., 4th ser., vol. 26, pp. 181-182,1908. 3 Am. Jour. Sci., 4th ser., vol. 21, p. 392,1906. COMPARISON OF PALEOZOIC SECTIONS IN SOUTHERN NEW MEXICO. 39 including the silicified portions of the overly­ limestone ledge forms a high cliff of dark color ing shale, appear at many places in irregular and in places makes a shelf or bench along the reefs projecting above the surface of the ground mountain front, as shown in Plates XV and or as ledges capping escarpments. In the XVIII, B. canyon of the Rio Percha, about a mile east of Sacramento Mountains.—The dark ledges of Hillsboro, the "upper limestone" is overlaid Montoya limestone are a prominent feature in unconformably by a bed of red and white the great series of limestones exposed in the conglomeratic quartzite 6 to 10 feet thick, higher part of the Sacramento uplift from the containing nodules that are possibly phos- vicinity of Alamo Canyon to a point near phatic. This stratum is overlain by a reddish- Grapevine Canyon. The relations are shown brown compact siliceous rock which may be in figures 14 (p. 51) and 15 (p. 54). a secondary deposit. Some of the strata carry The two members that occur in the San Richmond fossils, but the limit of beds that Andres and Franklin mountains and other should be classed as Montoya is not indicated. uplifts present characteristic features. The up­ San Andres Mountains.—The Montoya lime­ per one, 60 feet thick, consists largely of alter­ stone is a prominent feature in the great east­ nating thin beds of chert and limestone with ward-facing escarpment of the San Andres abundant Richmond fossils. The lower mem­ Mountains. It appears on the north side of ber is a dark-colored very massive limestone the igneous mass of the Organ Mountains and which crops out as a high cliff; its thickness is extends continuously northward to the north 75 feet at Dog Canyon and 120 feet at Alamo end of the range, where it thins out. It lies Canyon. At the latter place (see PL XIX, A)

Limestones and gypsum

Horizontal scale Vertical scale 4,OOO FEET

FIGURE 8. Section across the Caballos Mountains, southwest of Engle, N. Mex. gr, Granite; b, Bliss sandstone; e, El Paso limestone; m, Montoya limestone; f, Fusselman limestone (?); p, Percha shale (?); Iv, Lake Valley limestone (?); mg, limestone of Magdalena group; c, Cretaceous sandstone. on the El Paso limestone throughout this area, its base is gray sandstone and it is separated and it is overlain by the Fusselman limestone from the underlying El Paso beds by an to the south, as in the Franklin Mountains, and abrupt change in character of material and by the Percha shale north of the latitude of apparently there is a slight channeling of the Tularosa. The principal features of thickness, surface of the older formation. stratigraphy, and relations to other formations Fossils.—The fossils found in the Montoya are shown in figure 11 (p. 45). Some features limestone in the Franklin Mountains, north of are also shown in figure 9 (p. 42). El Paso, were identified by E. O. Ulrich. The Two members are everywhere present an fossils in the lower part comprised Eecepta- upper member of alternating thin beds of chert culites near R. oweni, Madurina manitobensis, and limestone, averaging about 75 feet in and Hormotoma major (?). The fossils in the thickness but thinning to 30 feet at Hays Gap; upper part are as follows: and a lower member of very massive dark- Streptelasma rusticum. colored limestone, about 100 feet thick, except Hemiphragma imperfectum. north of Rhodes Canyon, where it thins grad­ Monotryprella quadrata. ually. The lower member includes locally at Strophomena flexuosa. its base a sandstone that lies on the slightly Leptaena unicostata. uneven surface of the El Paso beds. This Ibed Dinorthis subquadrata. Platystrophia acutilirata. is 9 feet thick in the slopes 3 miles south of San Rhynchotrema capax. Andres Peak and 15 feet thick in San Andres Orthis near O. davidsoni. Canyon. At all places there is a sharp brjeak Plectorthis whitfieldi. at the base of the Montoya. The Montoya Parastrophia divergens. 40 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1917. These fossils are all of Richmond age. The From the basal beds were collected Erido- fossils from outcrops in Luna County, as iden­ trypa mutabilis (?), Batostoma cf. B. varium, tified by Mr. Ulrich, comprise the following: Dalmanella testudinaria var., and Zygospira Eurydictya cf. E. montifera. recurvirostra var. Dinorthis subquadrata. In the vicinity of Hillsboro Gordon 3 obtained Plectorthis whitfieldi. some corals identified by Ulrich as Columnaria Herbertella occidentalis. alveolata, Favosites asper (late Ordovician Dalmanella cf. D. meeki. Dalmanella near D. jugosa. variety), and Stromatocerium cf. S. pustulosum, Platystrophia acutilirata var. regarded as Richmond. Strophomena cf. S. subtenta. In the San Andres Range fossils were col­ Eafinesquina loxorhytes. lected at several localities. One ledge of cherty Leptaena unicostata. limestone in Sulphur Canyon yielded the fol­ Plectambonites saxea. Ehynchonella anticostiensis. lowing, determined by Edwin Kirk: Ehynchotrema capax Bythopora gracilis. Ehynchotrema perlamellosa. Bythopora cf. B. meeki. Zygospira recurvirostris. Bythopora striata. Streptelasma rusticum. Monotrypella quadrata. Cyrtodonta sp. Eridotrypa s.p. Vanuxemia sp. Dalmanella sp. Bumastus sp. Zygospira recurvirostris (Richmond variety). These forms are characteristic of the Rich­ Calymene. mond fauna that occurs in many parts of the In the canyon 3 miles south of San Andres Rocky Mountain region. No fossils were Peak Dinorthis subquadrata was found, and in found in the basal dark massive member. Cottonwood and Rhodes canyons were col­ In the Caballos Mountains Lee 1 collected lected numerous specimens of DalmaneUa tes­ Rajinesquina cf. R. Tcingi, Plectambonites saxea, tudinaria var. Plectambonites n. sp., Favosites asper, Zygospira Along the west front of the Sacramento recurvirostris, Rhynchotrema capax, Calapoecia Mountains fossils are abundant in the cherty canadense, and Platystrophia dentata var. layers of the upper member and many corals Many fossils were collected by Paige 2 in the are scattered through the lower massive dark Silver City area near the base and near the top limestone. From the lower member near Dog of the formation. The following were deter­ Canyon were obtained Halysites gracilis, Strep­ mined by E. O. Ulrich: telasma sp., Receptaculites sp.; and Rhyncho­ Streptelasma. trema capax. The cherty member at this Columnaria alveolata var. locality yielded abundant Dalmanella cf. D. Columnaria vicina. corpulenta. Tetradium sp. nov. Age and correlation.—Most of the fossils col­ Favosites asper. lected in the Montoya limestones are species Favosites cf. F. asper. Stromatocerium huronense. common in the Richmond of the Mississippi Dicranopora cf. D. fragilis. Valley and indicate that the formation com­ Plectorthis kankakeensis. prises two, or possibly three, representatives of Dalmanella tersa (?). the Richmond epoch. The lowest may be Dinorthis sp. correlated with the Fernvale of the Mississippi Dinorthis subquadrata. Valley, the lower part of the Bighorn dolomite Hebertella sinuata. Platystrophia n. sp., near P. acutilirata of Wyoming, the Whitewood limestone of the Strophomena sp. Black Hills, and the middle of the Fremont Ehynchotrema capax. limestone of eastern Colorado. The upper part Ehynchotrema anticostiensia. of the Montoya may be correlated with some Khynchonella neenah. portion of the upper Bighorn and probably Ctenodonta cf. C. coata. with the upper part of the Fremont and with Conradella sp. the Stony Mountain limestone of Manitoba. Lophospira cf. L. perangulata. L. medialis. It is not represented in the Black Hills and apparently not in the Mississippi Valley. The 1 Am. Jour. Sci., 4th ser., vol. 26, p. 181, 1908. 2 U. S. Geol. Survey Geol. Atlas, Silver City folio (No. 199), p. 4,1916. s U. S. Geol. Survey Prof. Paper 68, p. 227,1910. COMPARISON OF PALEOZOIC SECTIONS IN SOUTHERN NEW MEXICO. 41 Montoya is equivalent to part of the Lone The Fusselman limestone lies on the Montoya Mountain limestone of Nevada. Apparently limestone without conspicuous unconformity; the formation is absent in Arizona. at one locality 2 miles north of El Paso its lower layers carry small pebbles of black limestone SILURIAN SYSTEM. similar to some that occurs in certain beds of FTTSSELMAN LIMESTONE. the Montoya. Cooks Range.—The Fusselman limestone is Franklin Mountains and eastward.—The ex­ well developed in the Cooks Peak mining dis­ istence of rocks of Silurian age in New Mexico trict, where it is the principal rock containing was discovered by Gordon and Graton,1 who the ores of lead, silver, and zinc. It crops out found fossils at Silver City in 1905.1 Their extensively along the road from Cooks to the presence in the Franklin Mountains north of mountain top and along the slopes 2 miles to El Paso was announced by Richardson 2 in the north. It is a massive gray limestone of 1904, in a formation which he later designated exceptionally hard, compact texture, but its the Fusselman limestone.3 It is found that this upper part is cavernous in places, and in the limestone is separable in many parts of southern cavities, a short distance below the Percha New Mexico. shale, most of the rich ore pockets have been In its type locality the Fusselman limestone found. In this region the thickness of the is estimated to be about 1,000 feet thick and is formation is about 200 feet. The distinctive of considerable topographic prominence, cap­ Pentamerus occurs in places. The limestone ping the range for several miles and appearing appears in the south end of the range, near the in a number of detached knobs. It also crops fluorspar mines, but its relations are obscure out in the Hueco Mountains, 3 miles east of owing to igneous intrusions and faults. El Paso. The rock is mostly a massive light- Florida Mountains.—In places in the south­ colored magnesian limestone. Fossils are ern half of the Florida Mountains the Fusselman scarce on the whole, but they abound at a few limestone is absent in the varied overlaps. The horizons, especially a characteristic Pentamerus Percha shale apparently is also absent, and the that indicates upper Niagara age. Fusselman limestone where present is overlain The upper limit of the Fusselman is indis­ by the Gym limestone. tinct, and a thin representative of the Devonian Victorio Mountains.—The Montoya lime­ or Mississippian may possibly be present at the stone in Mine Hill is overlain by the Fusselman top. In an exposure 5£ miles west of south limestone, which constitutes the summit and from Hueco Tanks, 30 miles northeast of west side of the hill. The silver ore deposits El Paso, white limestone containing Silurian occur in this limestone, as in the Cooks Peak fossils is overlain by 100 feet of thin-bedded district. Its thickness appears to be somewhat gray limestone in which no fossils were found. more than 100 feet, but the top may be eroded. This formation dips much more steeply than In other ridges to the west it is cut off by faults the one below it. Overlying it with the same and also hidden by overlapping Gym limestone. steep dip are beds that carry Pennsylvanian Silver City region.—In the Silver City region fossils. In the Hueco Mountains a similar thin- the Fusselman limestone consists of 30 to 40 bedded gray to purplish limestone that contains feet of gray limestone and dolomitic beds, some chert and weathers buff separates the beds not plainly separated from the underlying containing Silurian and Pennsylvanian fossils Montoya. In its upper part there are abundant and dips at a less angle than the Silurian. On casts of the characteristic Pentamerus. the northwest flank of the Franklin Mountains, Cdballos Mountains.—Above the massive however, thin-bedded cherty limestone con­ cherty limestone with Montoya fossils in the taining Pennsylvanian fossils overlies the Caballos Mountains Lee 4 found 500 feet of Fusselman without discordance of dip. In the white to brown limestone, cherty in places, Van Horn area, farther east in Texas, Silurian, from which no fossils were obtained. These Devonian, and Mississippian representatives beds extend to the base of the limestone that are absent. carries Pennsylvanian fossils, and doubtless 1 Am. Jour. Sci., 4th ser., vol. 21, p. 394,1906. they include the Fusselman and possibly also 2 Texas Univ. Mineral Survey Bull. 9> p. 31, 1904. a Am. Jour. Sci., 4th sen, vol. 25, pp. 479-480,1908. Idem, vol. 26, p. 181. 42 SHOETEE CONTRIBUTIONS TO GENERAL GEOLOGY, 1917. strata of Devonian and Mississippian age. In tinctive fossils were collected. The upper the slopes 8 miles south of Shandon 300 feet of member is probably the 12 feet of pink lime­ black shale, probably the Percha, is present in stone referred to by Gordon,2 who obtained the section, and very likely it is, as usual, from it some fragments of corals regarded as underlain by the Fusselman. Silurian by Ulrich. According to Keyes3 this Robledo Mountain.—In a small exposure of limestone is dark colored and compact but cherty limestone not far below Pennsylvanian contains crevices filled with red clay which limestone on the northern slope of Robledo give it a pink appearance. Mountain, 5 miles south of Rincon, Lee 1 Mimbres Mountains.—It appears probable obtained Lophospira, Troclmsf, Bucania?, Tro- from the statements of Gordon4 that the Fus­ chonema, Eotomaria, and a pentameroid shell, selman limestone is present, at least in places, all suggestive of Silurian age and if so indicat­ in the Kingston-Hillsville region, but he re­ ing the Fusselman limestone. ports no fossils. The statement that the

Sheep Mtn

r,ooo 2,000 FEET

FIGUEE 9. Sections across the San Andres Mountains, Socorro and Dona Ana counties, N. Mex. A, Section across Sheep Mountain at Lava Gap; B, section southwest of San Nicolas Spring, in latitude 32° 35' N.; gr, granite; b, Bliss sandstone; e, El Paso limestone; m, Montoya lime stone; f, Fusselman limestone; p, Percha shale: Iv, Lake Valley limestone; mg, limestone of the Magdalena group. Lake Valley.—It was found that the lime­ "footwall lime" at Kingston and Tierra Blanca stones underlying the Percha shale in the Lake is similar to the ore-bearing sandstone in the Valley area (see fig. 10, p. 44) include 200 feet Cooks mining district is highly suggestive in or more of the Fusselman limestone, which this connection. contains many distinctive fossils. At the San Andres Mountains.—The Fusselman base, overlying beds that are probably Mon­ limestone is a conspicuous feature in the lime­ toya, there is an 80-foot bed of massive lime­ stone succession along the east front of the stone which weathers to light tint, and which San Andres Mountains from a point near Organ, yielded no fossils but is tentatively regarded where it is cut off by igneous rocks, to a point as the Fusselman, as in other regions. Next 2 or 3 miles north of Sulphur Gap, where it above are 40 feet of cherty beds, somewhat thins out. Some of its relations are shown in like the Montoya in character but carrying figures 9 and 11. The thickness ranges from distinctive fossils. These beds grade upward 220 feet in the southern part of the range to into 80 feet or more of massive limestone of light color, constituting the summit of Quartz- 120 feet in the middle part and at Sulphur Gap, ite Ridge for some distance and extending and there is rapid thinning toward its north­ down its east slope to the Percha shale in the s' U. S. Geol. Survey Prof. Paper 68, pp. 227, 277,1910. valley. In cherty layers on this slope dis- 8 Keyes, C. R., Genesis of the Lake Valley, New Mexico, silver deposits: Am. Inst. Min. Eng. Trans., vol. 39, p. 146, 1909. i Am. Jour. Sci., 4th ser., vol. 26, p. 185,1908. « U. S. Geol. Survey Prof. Paper 68, p. 227, 1910. COMPARISON OF PALEOZOIC SECTIONS IN SOUTHERN NEW MEXICO. 43 ern termination. The formation comprises cliff of limestone of the upper member of the two members an upper bed of hard dark- formation. This cliff is well shown in Plate colored massive limestone, marked by a cliff XIX, A. at most places, and a lower member of fine­ Fossils and correlation.—In general fossils grained limestone, most of which weathers are rare in the Fusselman limestone, but at nearly white. The upper member contains some localities a few of the beds yield abundant distinctive fossils, but the lower one has remains. The most common and character­ yielded no fossils and is arbitrarily placed in istic form is a Pentamerus, but many corals the formation because of its distinctness from occur at some places. the underlying cherty beds, which are char­ The fossils found by Richardson 1 in the acteristic of the upper part of the Montoya. Franklin Mountains included Amplexus, Favo- The massive bed gives rise to a shelf at the sites, and numerous casts of Pentamerus, all base of the slope of the overlying Percha indicative of Niagara age. The same Penta­ shale. Its thickness is 80 feet in the south­ merus is abundant in the upper beds near ern part of the range, but it gradually thins Cooks and Silver City. On the south side of northward to 40 feet in Lostman Canyon, 30 Mine Hill, in the Victorio Mountains, numerous feet in Hembrillo Canyon (see PI. XV, A), and corals were collected, including Heliolites mega- 25 feet in Sulphur Gap. The lower limestone stoma, Favosites cf. F. venustus, Cyathophyl- is 140 feet thick in the south end of the range, lum cf. C. radicula, Halysites catenulatus (large but it thins somewhat north of San Andres and small varieties), and Syringopora sp., also Peak. It is nearly 100 feet thick in Sulphur an orthoid suggesting RTiipidomella hybrida. Gap but thins out and disappears in slopes These were determined by E. O. Ulrich, who north of the gap. In places some of its beds regards them as probably late Niagara and are soft and earthy, as in Lostman Canyon, similar to a coral fauna found by Kindle in the but most of it is a fine-grained, compact dark- Laketown dolomite of northeastern Utah. gray rock that weathers to very light gray or From the upper ledge of the limestone in the nearly white so that it is conspicuous in all San Andres Mountains 1^ miles southwest of outcrops. San Nicolas Spring, or about 22 miles north­ Sacramento Mountains. — The Fusselman east of Las Cruces, the writer collected the limestone makes a prominent ledge along the following forms, determined by Edwin Kirk: east front of the Sacramento Mountains from Pentamerus sp., CyatJiophyUum sp., Heliolites Alamo Canyon to a point near Agua Chiquita sp., and Hormotoma sp. a distinctive Fussel­ Canyon. Its disappearance to the north and man fauna. south is due to the downward pitch of the anti­ The Pentamerus was observed at many other cline that brings it to the surface. (See fig. 14, localities in the San Andres Mountains as far p. 51.) The thickness ranges from 105 to 130 north as Sulphur Gap and also in the east front feet; the maximum is reached in Alamo Canyon. of the Sacramento Mountains. (See PL XIX, A, p. 37.) As in the San Andres Fossils were collected at three horizons in the Mountains and other uplifts, the formation com­ Fusselman limestone at Lake Valley, all from prises two members an upper one, about 50 beds above the 80-foot member that weathers to feet thick, of hard dark limestone carrying dis­ a light color. Cherty layers not far above this tinctive fossils, and a lower one of compact, member yielded Monomerellan.sp. and ZapTiren- fine-grained gray limestone that weathers tis sp. In cherty layers about 100 feet higher nearly white, and is 60 feet thick in Dog Canyon Monomerella was very abundant, and near the and 85 feet thick in Alamo Canyon. The lower top, about 30 feet below the base of the Percha member yielded no fossils, but is arbitrarily in­ shale, were collected ZapJirentis sp., Amplexus cluded in the formation because of its unlike- sp., and a variety of Pentamerus oblongus that ness to underlying distinctively cherty beds at is characteristic of the upper beds in other the top of the Montoya limestone. It consti­ regions. tutes a steep light-colored slope below the dark U. S. Geol. Survey Geol. Atlas, El Paso folio (No. 166), 1909. 44 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1917.

DEVONIAN SYSTEM. part fine grained, with no fossils. The upper PERCHA SHALE. member consists of 10 feet of bluish thin- General relations.—Only a small part of bedded limestone made up largely of chert in Devonian time is now represented in New elongated nodules and containing no fossils. Mexico. The deposits consist of the Percha According to Keyes, "it contrasts strikingly shale, in which Gordon and Graton 1 found with the massive compact blue limestone lying Devonian fossils in the Lake Valley and Kings­ immediately above." ton regions. The formation is named from In the Kingston-Hillsboro region portions of Percha Creek, near Kingston. It overlies the the basal beds are altered to a fine-grained red Fussehnan limestone, but in places it is absent to black siliceous rock of a jaspery character, and the Fusselman is overlain by beds of Car­ somewhat brecciated and seamed with quartz. boniferous age. Notwithstanding the long in­ The quartz seams are believed to have been terval between the Fussehnan and Percha formed by heated siliceous water. epochs, the beds show no noticeable difference Cooks Range.—In Luna County the Percha in attitude, but there is an abrupt change from shale appears in Cooks Range and Fluorite massive limestone to black shale. Ridge, where it has a thickness of 175 feet. Lake Valley and Hillsdale region.—In the The rock is a uniform black shale of moderate Lake Valley mining region the Percha shale hardness separating into thin brittle layers. appears in a narrow outcrop that extends for It crops out extensively along the limestone about 3 miles along a valley just west of the slopes on both sides of the range northwest of ridge of Lake Valley limestone, as shown in Cooks, where it immediately overlies the ore-

w. Mine Hill E-

Horizontal scale Vertical scale 800 ... 9______800 FEET 400 800FEET FIGURE 10. Section through the Lake Valley mining district, Sierra County, N. Mex. e, El Paso limestone; m, Montoya limestone, with sandstone (ss) at base; f, Fusselman limestone, with white limestone (w) at base; p, Percha shale, including lower member (d) and upper member (c); n, nodular limestone; Iv, Lake Valley limestone, including ore horizon, or "footwa 11 lime" (o), shale and thin limestone (s); limestones, upper beds cherty (b), and andesite and rhyolite (a). figure 10. It is mentioned in several pub­ bearing Fusselman limestone. It is absent in lished reports regarding the relations of the the Victorio Mountains. ores of the district. Two members were recog­ Florida Mountains.—In the southern part nized by Gordon 1 an upper grayish-yellow to of the Florida Mountains there is a dark shale blue shale 60 feet thick (c in fig. 10) and a which closely resembles the Percha but which black fissile shale 100 feet thick (d in fig. 10). appears to be in the Gym limestone succession, Neither of these is fossiliferous at Lake Valley, though this apparent relation may be due to but beds near the top of the upper member overlap or faulting. yielded an extensive fauna, at Hillsboro and Silver City.—The Percha shale crops out in Kingston. Keyes 2 stated that the overlying several small areas about Silver City, and it nodular limestone, 50 feet thick, at Lake Val­ also occurs in the vicinity of Georgetown and ley is also Devonian and proposed for it the Hanover, a few miles to the east. The maxi­ name Barenda. He described it as consisting mum thickness in this area is 500 feet, but in of three distinct members. The lowest one is places the amount is much less. a massive, compact gray limestone, like Caballos Mountains.—Gordon3 suggested that lithographic stone, 10 feet thick, weathering the black shale in the Caballos Mountains rusty brown and carrying a "typical late is the Percha, but he reported no fossils. Devonian fauna." The medial member, 30 In places, especially to the north, the shale is feet thick, is gray thin-bedded limestone, in absent and the Pennsylvanian limestone lies on the Montoya or higher limestones. According i Am. Jour. Sci., 4th ser., vol. 21, p. 394,1904. * Am. Inst. Min. Eng. Trans., vol. 39, p. 147,1909. 8 U. S. Geol. Survey Prof. Paper 68, p. 226, 1910. COMPARISON OF PALEOZOIC SECTIONS IN SOUTHERN NEW MEXICO. 45 to Lee,1 in the section 8 miles south of Shandon in blue shales near the upper part of the upper 300 feet of black shale intervenes between member at Kingston and at a locality 2 miles "late Ordovician" cherty limestone and lime­ east of Hillsboro. The following were identi­ stones of Carboniferous age. fied by Girty and Kindle: 4 Franklin Mountains. As Kichardson 2 found Zaphrentis sp. Carboniferous and Silurian fossils very near Spirorbis sp. together in the Franklin Mountains, it appears Leptaena rhomboidalis. that the Devonian is not represented in the Productella coloradensis var. plicatus. Productella spinigera. succession of limestones in that range. Productella hillsboroensis. Sacramento Mountains.—The Devonian is Schizophoria striatula var. australis. probably represented in the section exposed Camarotoechia (Plethorhyncha) endlichi. along the west front of the Sacramento Moun­ Camarotoechia contracta. tains southeast of Alamogordo, in the lower Eunella sp. part of the shale that lies on the Fusselman Athyris coloradensis. Pugnax pugnus. limestones, but the fossils found were not Spirifer whitneyi. sufficiently well preserved to be determined Spirifer whitneyi var. animasensis. specifically. Spirifer notabilis.

Soytherr> SanAndres Deadman and Hembrillo Sulphur Gap Cottonwood Rhodes Salinas Peak Canyon.- Lostman canyons Canyon Canyon Canyon to Hays Gap

Magdalena g^oup (lower part only) CARBONIFEROUS Lake Valley limestone' DEVONIAN Percha shale Fusselrna SH.URIAN limestone "

Montoya limestone Dark.massiv. Sandstone ORDOVICIAN El Paso limestone

CAMBRIAN Bliss sandstone— m, Magdalena fossils PRE-CAMBRIAN {Granite and schist Iv, Lake Valley fossils

FIGXJEE 11. Columnar sections showing stratigrapnic variations in lower Paleozoic rocks in the San Andres Mountains, Dona Ana and Socorro counties, N. Mex. San Andres Mountains.—Shale with Upper Syringospira prima. Devonian fossils extends along the San Andres Reticularia spinosa. Mountains from a point 2 miles northeast of Meristella barrisi. Organ, where igneous intrusions cut off the Fossils found by Paige in the Percha shale at succession, nearly to Mockingbird Gap. Its Silver City are as follows: thickness is 50 feet or more, and it crops out Schizophoria striatula var. australis. Productella coloradensis. in a slope between the prominent ledge of Productella spinigera. massive limestone above and a shelf or cliff Productella laminatus. of Fusselman or Montoya limestone below. Camarotoechia contracta? The basal beds are black shale, above which are Camarotoechia (Plethorhyncha) endlichi. layers of slabby and nodular limestone sepa­ Pugnax pugnus. Spirifer notabilis. rated by gray shale. Possibly in places the Spirifer whitneyi. uppermost layers of shale are Carboniferous. Reticularia spinosa. The fossils found were mostly in the medial Athyris coloradensis. beds. Some of the relations are shown in Aviculipecten n. sp. figures 9 and 11 and Plates XV (p. 33) and Bellerophon sp. Euomphalus eurekensis? XVIII (p. 36). Corals and bryozoans. ' Fossils.—The Devonian fossils reported by Gordon and Graton 3 were found in abundance The following fossils were found in the Percha shale in 1915 a mile south of Capitol 1 Am. Jour. Sci., 4th ser., vol. 26, p. 182, 1908. 2 U. S. Geol. Survey Geol. Atlas, El Paso folio (No. 166), p. 4, 1909. 4 See Kindle, E. M., The Devonian fauna of the Ouray limestone: s Am. Jour. Sci., 4th ser., vol. 21, p. 394,1904. U. S. Geol. Survey Bull. 391, 1909. 46 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1917. Peak, in the northern part of the San Andres Age and correlation.—The fossils from the Mountains. They were identified by Edwin Percha shale are regarded by Mr. Kirk as in­ Kirk: dicating that the formation is late Devonian, equivalent to the lower part of the Ouray Tropidoleptus carinatus var. Alveolites sp. limestone and the upper part of the Martin Spirifer n. sp. limestone (Upper Devonian) of the Bisbee Stropheodonta near S. arcuata Hall. region, Ariz., and the upper 2,000 feet of Productella hallanus. Nevada limestone of the Eureka district, Atrypa reticularis. Nev. As the lower beds of the Percha shale Atrypa hystrix. Schizophoria striatula var. australis? in the type locality have not yielded fossils, Diaphosostoma sp. the formation may represent a somewhat greater range than is indicated by the collec­ On the north slope of Sheep Mountain, in tions recorded. The beds in the San Andres Lava Gap, a mile farther south, were obtained Mountains appear to carry a smaller number ZapJirentis, Atrypa reticularis, Cyrtia n. sp., of the typical lower Ouray forms than are Productella Tiallanus, and Stropheodonta near present in Lake Valley, and more of the forms S. arcuata. In Sulphur Gap, which is not far characteristic of the Martin limestone and north of the latitude of Alamagordo, the fol­ Nevada limestone. However, all the New lowing forms were collected from medial beds: Mexico collections are too fragmentary to per­ Atrypa hystrix. mit precise correlation. Atrypa reticularis. Schizophoria striatula var. australis. CARBONIFEROUS SYSTEM. Pugnax pugnus. Camarotoechia contracta? GENERAL FEATURES. Chonetes sp. Stropheodonta n. sp. In southern New Mexico rocks of Carbon­ Spirifer whitneyi var. animasensis. iferous age comprise representatives of the Spirifer sp. earlier part of Mississippian and of a large In a canyon 3 miles south of San Andres part of Pennsylvanian and Permian time, the Peak were found Rhipidomella sp., Spirifer later Mississippian being unrepresented there, sp., and (Thonetes sp. In Cottonwood Canyon as in most other portions of the West. In the the shale yielded Spirifer whitneyi. Lake Valley region and to the south the for­ In nodular beds in the middle of the forma­ mation of lower Mississippian age is the Lake tion in San Andres Canyon were found the Valley limestone, which appears in most of following: the uplifts between latitudes 32° 20' and 34°. The rocks of supposed Mississippian age in the Zaphrentis sp. Magdalena region are known as the Kelly Fenestella sp. limestone. The beds of the Pennsylvanian Productella cf. Productella coloradoensis var. plicata. Ambocoelia sp. and Permian series occur throughout the area Schizophoria striatula var. australis. and in the adjoining States. They comprise Leiorhynchus? sp. a great thickness of limestone, which to the Spirifer cf. Spirifer utahensis. northeast is accompanied by the red sandstone Reticularia undifera var. and shale of the Abo sandstone and many Phacops sp. thick deposits of gypsum. At the same horizon in Hembrillo Canyon In Luna County the formations of the Penn­ were obtained Fenestella, Atrypa reticularis, sylvanian and Mississippian series are separated Pugnax pugnus, Cyrtia sp., Stropheodonta near by a hiatus of considerable amount, and there S. arcuata, Gypidula sp., and Productella sp. is an overlap of the higher limestone toward A few fragmentary fossils were collected from the south. Thus, in the Florida, Victorio, black shale a few feet above the Fusselman and Franklin mountains the later Carbonifer­ ledge near Dog Canyon, in the west front of ous rocks lie directly on the Silurian limestone, the Sacramento Mountains, but they could not and the Mississippian and earlier Pennsylvanian be determined. Mr. Kirk recognized one of (Magdalena group) appear to be absent. The the brachiopods as Meristella or some closely Manzano group, or later Carboniferous, is allied genrs, almost certainly Devonian. represented by a thick limestone formation, COMPAEISON OF PALEOZOIC SECTIONS IN SOUTHERN NEW MEXICO. 47 the Gym limestone. A still younger forma­ limestone underlain by the Percha shale and tion, separated as the Lobo and tentatively at the top eroded and in part overlain by Ter­ assigned to the Triassic, may possibly represent tiary igneous rocks. (See fig. 10, p. 44.) Dis­ the upper part of the Manzano. tinctive lower Carboniferous (Mississippian) A comparison of the Carboniferous rocks of fossils were found in these limestones by Cope3 southern New Mexico with those of Arizona in 1881 and by others at intervals later, notably shows close similarity. The Lake Valley lime­ by Springer,4 who published a detailed list of stone has the same fauna as the Modoc lime­ many forms, including an extensive crinoid stone at Clifton,1 180 feet thick, and the Esca- fauna closely similar to the lower Burlington "brosa limestone of the Bisbee region,2 700 feet of Iowa. The section given by Springer is as thick. The Magdalena group is represented in follows: whole or part by the Tule Spring limestone of Section of Lake Valley limestone at Lake Valley mining Clifton, 500 feet thick, and by part of the Naco camp, N. Mex. limestone of the Bisbee region. The Naco, Feet. 9. Cherty limestone, with irregular flinty masses, in which is 3,000 feet or more thick, appears to places light colored and full of crinoids...... 30 include in its upper part a thick representative 8. Limestone, heavy bedded, pink to drab; marly of the Hueco limestone of western Texas. partings; many crinoids, corals, and other fossils.. 40 Farther west and north in Arizona, especially 7. Limestone, thin bedded, bluish, mostly shaly; in the Grand Canyon region, the Redwall lime­ many crinoids, corals, bryozoans, and other fos­ stone, 1,000 feet or more thick, comprises rep­ sils...... 20 6. Limestone, hard, granular, sandy, pinkish to blu­ resentatives of both the Pennsylvanian and the ish...... 6 earlier Mississippian, the Pennsylvanian beds 5. Shale, light yellow, with flinty nodules...... 15 being equivalent to the Magdalena group. The 4. Limestone, irony, coarse, irregularly bedded, with overlying red beds of the Supai formation, marly partings; corals and crinoid fragments.... 30 1,200 feet thick, probably correspond to the 3. Sandstones, dark brown, heavy bedded and hard be­ low, shaly above...... 12 Abo sandstone (red sandstone), 700 to 1,000 2. Shale, light yellowish, with irregular flinty masses; feet thick, at the base of the Manzano group. no fossils-...... 8 The overlying Coconino sandstone and Kaibab 1. Slope covered by debris. limestone, the latter in places containing gyp­ Beds 7 and 8 yielded most of the fossils. sum deposits, are probably equivalent to the The beds below No. 7 Springer referred to the great succession of sandstone, gypsum, and Kinderhook group. No fossils were reported limestone that constitute the upper part of the from bed 3. A section given by Gordon,5 who Manzano group in New Mexico. G. H. Girty visited the locality in 1905 is as follows: regards the fauna of the upper limestone of the Manzano group as closely similar to that of the Section of Lake Valley limestone at Lake Valley, N. Mex. Kaibab limestone. Representatives of the 9. Capping of andesite. Feet. Supai and Abo red beds are lacking to the 8. Limestone, coarse, subcrystallLne, yellowish white; moderately thick beds, some cherty; many cri­ south, notably in southern New Mexico, in noids and other fossils; top eroded...... 60 southwestern Texas, and in the Naco limestone 7. Shale, blue; includes thin bluish limestone beds; succession of the Bisbee region. many fossils but fewer crinoids than No. 8...... 75 6. Limestone, grayish blue, hard, more or less silice­ LOWER MISSISSIPPIAN LIMESTONES. ous, called "blue limestone" in the mines. Lo­ cal breccia of flint at top. At base 5-foot bed of Lake Valley region.—The Lake Valley lime­ coarse crystalline yellowish-white limestone.... 25 stone received its name from the Lake Valley 5. Limestone, compact, grayish, filled with nodular mining district, where it crops out in an area chert; partings mostly thick...... 50 about 3 miles long and half a mile wide. In Percha shale. that district it consists of about 200 feet of 3 Cope, E. D., Geology of the Lake Valley mining district: Am. Natu­ ralist, vol. 15, pp. 831-832, 1881. 1 Lindgren, Waldemar, U. S. Geol. Survey Geol. Atlas, Clifton folio 4 Springer, Frank, on the occurrence of the Lower Burlington limestone (No. 129), 1905. in New Mexico: Am. Jour. Sci., 3d ser., vol. 27, pp. 97-103,1884. 2 Ransome, F. L., U. S. Geol. Survey Geol. Atlas, Bisbee folio (No. 112), 6 Gordon, C. H., Mississippian formations in the Rio Grande valley, 1904. N. Mex.: Am. Jour. Sci., 4th ser., vol. 24, pp. 58-64,1907. 48 SHOETER CONTRIBUTIONS TO GENERAL GEOLOGY, 1917. No. 5 (n, fig. 10) is the nodular limestone of some beds, and the lower ones yield many Mis- Clark,1 who described the region in considerable sissippian forms. detail. Keyes,2 however, placed this member Mimbres Mountains. Gordon 4 states that in the Devonian and called it the 'Barenda the Lake Valley limestone crops out at many limestone. points along the east side of the Mimbres Moun­ Cooks Range.—In Luna County the Lake tains, and he gives the section reproduced here Valley limestone occurs only in Cooks Range, as figure 12, showing its relations in that re­ where its thickness is between 600 and 700 gion. At Kingston the formation consists of feet. It consists mainly of light-gray, massive thick-bedded blue limestones with nodular to slabby limestone, with several intercalated cherty beds and shaly thin-bedded limestone, members of shale, partly limy. The limestone 100 to 125 feet in all. Many distinctive fossils members crop out mostly as cliffs 80 to 100 feet occur in it. high, separated by shaly slopes. The basal Caballos Mountains.—It is not unlikely member consists of 150 feet of bluish-gray lime­ that some Lake Valley limestone is included in stone, with some chert in its lower part. The the great section on the west front of the Ca­ upper member contains some thick bodies of ballos Mountains, but no data are available on white chert and cherty limestone. A small this point. body of Lake Valley limestone lies on the Percha Magdalena Mountains.—The Kelly lime­ shale in Fluorite Ridge, at the south end of stone, or so-called "Graphic Kelly" limestone, Cooks Range, near Cooks Peak. It is cut by the ore-bearing formation in the silver-lead

bs HilEsboro Iv,

FIGURE 12. Section from the Mimbres Mountains eastward through Kingston and Hillsboro, N. Mex. (After Gordon.) gr, Granite; b, Bliss sandstone; e-f, Mimbres limestone [El Paso, Montoya, and Fusselman]; p, Percha shale; Iv, Lake Valley limestone; mg, Magdalena group; m, Manzano group; pg, Palomas gravel; bs, basalt sheet; a, andesite; ry, rhyolite; d, dike. the great porphyry intrusion and interrupted mines at Kelly, is supposed to be of Mississip- by several faults. Fossils are abundant in the pian age, Herrick 5 and Keyes 6 having reported limestone in this locality. that crinoids were found in it. This limestone Silver City region.—In the Silver City region is white and crystalline, and occurs in thick beds, the two divisions of the Carboniferous are about 125 feet in all, lying on pre-Cambrian grouped together by Paige 3 as the Fierro lime­ schist and granite. (See PI. XIX, B.) Near stone. The rocks are limestones, ranging in the middle is a 5-foot layer of dark-blue non- color from light gray to dark blue or purplish. crystalline rock, weathering yellowish drab, West of Silver City the upper half is chiefly which the miners call "Silver Pipe limestone." light gray or light blue and the lower part Keyes 6 gives the following section of the darker blue. All but the upper 100 feet is limestones in the Magdalena Mountains, includ­ cherty, and near the base there is some red chert. ing the Kelly limestone, in which Mississip- Some thin, more or less shaly beds are included. pian crinoids were obtained: The Fierro limestone varies in thickness be­ cause of the unconformity at its top, and doubt­ Section of limestone in Magdalena Mountains. Feet. less also between its two divisions, but the Limestone, blue, heavy bedded, with thick shale maximum thickness is about 800 feet. It is partings...... 300 widely distributed, constituting much of the Shale, sandy, greenish-...... 200 range northwest of Silver City, part of Lone Sandstone, greenish, micaceous, soft...... 50 Sandstone, quartzite, pebbly (base of Magdalena Mountain, and areas near Fort Bayard and group)...... 60 north of Santa Rita. Fossils are abundant in * TJ. S. Geol. Survey Prof. Paper 68, p. 229,1910. 1 Clark, ElUs, The silver mines of Lake Valley, N. Mex.: Am. Inst. B Herrick, C. L., Laws of formation of New Mexico mountain ranges: Min. Eng. Trans., vol. 24, pp. 138-169, pi., 1884. Am. Geologist, vol. 33, p. 310,1904. *Am. Inst. Min. Eng. Trans., vol. 39, p. 147, 1909. 6 Keyes, C. R., Northward extension of the Lake Valley limestone: 3 U. S. Geol. Survey Geol. Atlas, Silver City folio (No. 199), p. 5,1916. Iowa Acad. Sci. Proc., vol. 12, pp. 169-171,1904. COMPARISON OF PALEOZOIC SECTIONS IN SOUTHERN NEW MEXICO. 49 Feet. Mississippian series in the west front of the Shale, dark, siliceous (Mississippian) ...... 50 Limestone, gray, crinoidal (Mississippian)...... 45 Sacramento Mountains but gave but little in­ Limestone, heavy bedded, crinoidal ('' upper vein ") 30 formation as to the conditions of occurrence. Limestone, blue, impure, fine grained, siliceous The bed was stated to be 560 feet above the ("Silver Pipe lime")...;...... 8 base of the section in Dog Canyon (see PI. Limestone, gray, subcrystalline (contact vein)..... 60 XIX, A), and the thickness of the "Burlington On schists, granite, greenstone, etc. limestone," as Herrick termed it, is 250 feet. San Andres Mountains.—The Lake Valley In 1908, G. H. Girty examined a section east of limestone occurs in an area of considerable Alamogordo, in which 1,500 feet of limestone extent in the San Andres Mountains, but it is and shale containing Pennsylvanian fossils, not thick and may be discontinuous. In the were found to be underlain by 150 feet of lime­ central part of the range a heavy bed of lime­ stone containing Mississippian forms. Some of stone overlying the Percha shale yielded lower the same species were collected in Alamo Can­ Mississippian (Lake Valley) fossils at several yon, a few miles farther south, by G. B. Rich­ localities, notably in San Andres Canyon and ardson, and also in 1915 by the writer. An on the slopes 3 miles south of San Andres Peak, unpublished section, kindly furnished by Mr. and also at a locality, shown in figure 9 (p. 42), Girty, is as follows: west of San Nicolas Spring, or about 16 miles Section of Carboniferous racks in ridge N. 63° E. of Alamo­ northeast of Las Cruces. The greatest thick­ gordo, N. Mex. ness observed was in San Andres Canyon and Feet. northward for 10 or 12 miles, where the amount 43 Massive limestone...... 50± may be 100 feet or more. The principal bed 42. Thinner beds and concealed...... 100 ± that yielded Lake Valley fossils is a massive 41. Dark limestone...... 50 ± 40. Concealed...... 30 limestone, cherty in its upper part; but some 39. Dark limestone...... 3 overlying softer beds and a higher massive bed 38. Concealed...... 50 may possibly be included in the formation. 37. Soft greenish gritty sandstone...... 10 In San Andres Canyon the higher massive bed 36. Concealed; debris, limestone and thin greenish is capped by 28 feet of hard gray sandstone, sandstone...... 100 35. Dark massive limestone, weathering brown..... 25 immediately above which is shaly limestone 34. Concealed...... 20 containing Magdalena fossils. In Hembrillo 33. Dark limestone...... 5 Canyon the only member present is the first 32. Sandy shale, partly concealed...... 10 massive bed that caps the Percha shale, for the 31. Earthy limestone (fossils)...... 4 strata next above carry Pennsylvanian fossils. 30. Dark shale above (20 feet), concealed below.... 50 29. Argillaceous and calcareous shale (fossils)...... 10 This bed extends northward past Salinas Peak 28. Dark siliceous limestone...... 10 to and beyond Hays Gap, where, however, no 27. Greenish sandy shale...... 15 fossils were found in it. In Sulphur Canyon 26. Greenish-brown gritty sandstone...... 10 it is 60 feet thick and is capped by 30 feet of a 25. Shaly material...... 5 peculiar sandstone, including considerable con­ 24. Thin dark siliceous limestone...... 10 23. Concealed; probably thin impure limestone.... 15 glomerate of large pebbles and fragments of 22. Massive dark limestone...... 10 white chert. This material is presumably basal 21. Concealed...... 15 Magdalena. Some of it appears also in Lost- 20. Siliceous limestone below, concealed in middle, man Canyon. In Deadman Canyon the mas­ purer and fossiliferous limestone above...... 20 sive limestone bed above the Percha shale is 80 19. Greenish gritty sandstone, thin bedded below, massive in middle, thinner above...... 60 feet thick and grades upward into 50 feet of 18. Partly concealed; upper part with thin black limestone with cherty layers. In Rhodes Can­ limestone, weathering bluish and yellowish.. 50 yon the ledge is only 25 feet thick, and in Lava 17. Lower 30 feet probably thin gritty sandstone; Gap it is 30 feet thick. The outcrop at the lat­ upper 20 feet massive; some layers calcareous, ter place is shown in Plate XVIII, B. with quartz pebbles and fossils ...... 50 16. Gritty sandstone, calcareous below and fossili­ Sacramento Mountains.—In 1900 C. L. Her- ferous- ...... 10 rick 1 announced the discovery of fossils of the 15. Dark-brown limestone, somewhat shaly, many fossils...... 10 1 Herrick, C. L., Univ. New Mexico Bull., vol. 2, No. 3, p. 8. The geology of the white sands of New Mexico: Jour. Geology, vol. 8, pp. 14. Poorly exposed; probably thin dark siliceous 112-128, 1900. limestone, weathering brown, poor fossils.... 100± 50 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1917. Feet. occur on the south side of the Sierra Ladrones, 13. Black limestone, siliceous, weathering brown... 3 Socorro County, where in 1905 W. T. Lee* 12. Poorly exposed; probably thin impure lime­ stone and a few ledges of dark cherty lime­ obtained distinctive Mississippian fossils. (See stone; poor fossils...... 50 list on p. 52.) The locality was in the canyon 11. Light-colored sandstone and fine conglomerate; of Rio Salado, about one-eighth of a mile from poorly exposed...... 100± the granite ledges and therefore very near the 10. Shale with calcareous layers; fossils...... 30 base of the sedimentary succession. Not far 9. Dark impure limestone...... 15 above are limestones with fossils of Pennsyl- 8. TInexposed; probably thin sandstone and then impure limestone; Productus com and P. vanian age, and in 1913 the writer found Penn- semireticulaius in debris...... 100 sylvanian fossils within 3 or 4 feet of the gran­ 7. Whitish and rusty gritty sandstone, and fine ite on the northwest side of the mountain. conglomerate, not well exposed; perhaps as Evidently the Salado Canyon exposure is much as...... 300 either an outlying lens of the Mississippian 6. Light-colored crinoidal limestone; some very limestone or an extension northward from soft and weathering to gravel...... 75 5. Dark siliceous limestone with chert in bands... 30 Magdalena Mountain. The Mississippian is 4. Massive, rather soft calcareous shale; big crin- not present east of Socorro and in the Man- oid stems and Schiwphoria...... 5 zano, Sandia, Zuni, Nacimiento, and Rocky

E. w. Sacramento Mts

Horizontal scale Vertical scale O 4.00OFEET

FIGUKE 13. Section of the west front of the Sacramento Mountains, 12 miles southeast of Alamogordo, N. Mex. gr, Granite; b, sandstone (Bliss?); e, El Paso limestone; m, Montoya limestone (dark massive limestone, overlain by cherty limestone); w, limestone, white when weathered (Fusselman?); f, Fusselman limestone; mf. shaly limestone, with Mississippian fossils. 3. Dark limestone and thin shale interbedded; mountains, where rocks of the Pennsylvanian limestone with '' Caudagalli "...... 20 series lie directly on pre-Cambrian granite. 2. Same as No. 1 but more massive...... 15 1. Dark bluish-gray calcareous shale, thin bedded Fossils.—In the type locality at Lake Valley, and rather massive; base not seen. from beds 7 and 8 in the section given on page Fossils of Mississippian age were obtained 47, were obtained the following fossils. The from bed 6 (see list on p. 52), as well as in the identifications were made by G. H. Girty, lower beds, and this member is tentatively except those of the crinoids, which were made regarded as the top of the Mississippian, by Frank Springer: although possibly bed 7 should also be in­ Cladochonus sp. cluded. Beds 1 and 2 extend down to the edge Favosites aff. F. valmeyerensis. of the valley fill. The strata containing Missis­ Zaphrentis sp. sippian fossils extend all along the west front of Amplexus aff. A. fragilis. the range, from a point opposite Alamogordo Platycrinus peculiaris. nearly to Grapevine Canyon. The most abun­ Platycrinus parvinodus. Platycrinus pileiformis. dantly fossiliferous beds are in the 100-foot Periechocrinus whitei. member of shales and slabby limestone lying Megistocrinus evansi? between a massive ledge of coarse-grained lime­ Dorycrinus unicornis. stone and the top of the cliff of Fusselman Physetocrinus lobatus. limestone. Physetocrinus planus. The relations of these Mississippian beds are Steganocrinus sculptus. shown in figures 13 and 14, the latter showing Fistulipora americana. Cheilotrypa? sp. the long arch extending along the mountain Fenestella sp. front east-southeast of Alamogordo. (See also Pinnatopora sp. Pk. XX and XXI.) Rhombopora sp. Sierra Ladrones.—The northernmost known 1 Gordon, C. H., Mississippian formations in the Rio Grande valley, rocks of Mississippian age in New Mexico N. Mex.: Am. Jour. Sci., 4th ser., vol. 24, p. 58,1907. U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 108 PLATE XX

VIEW LOOKING ttOUTHbAST ALONG WEST FRONT OF SACRAMENTO MOUNTAINS FROM ALAMOGORDO, OTERO COUNTY, N. MEX. A, Mouth of Alamo Canyon; O, canyon with small orchard at its mouth; F, northwest-southeast fault; S, San Andres Canyon; e, El Paso limestone; m, Montoya limestone; f, Fusselman limestone; mf, limestone with Mississippian fossils above which are Pennsylvanian limestones. U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 108 PLATE XXI

VIEW ALONG WEST FRONT OF SACRAMENTO MOUNTAINS AT AGUA CHIQUITA CANYON, OTERO COUNTY, N. MEX. Looking southeast, m, Montoya limestone; e, El Paso limestone; gr, granite. COMPARISON OF PALEOZOIC SECTIONS IN SOUTHERN NEW MEXICO. 51

Crania aff. C. missouriensis. Sp iriferina sp. Schizophoria aff. S. swallowi. Athyris lamellosa. Productus aff. P. burlingtonensis. Cliothyridina aff. C. Productus aff. P. arcuatus. . glenparkensis. Productus aff. P. sampsoni. Platyceras aff. P. equi- latera. La Luz Canyon ' Pustula n. sp. I Pustula sp. Platyceras sp. B a, Rhynchopora occiden talis. Orthonychia sp. j§ Camarotoechiaaff.C. metallica. Phillipsia aff. P. peroc- ^ Dry Ca lyon Sphifer aff. S. grimesi. cidens. |3 Spirifer aff. S. vernonensis. Proetus aff. P. logan- 1 Brachythyris aff. B. suborbicularis. ensis. | Delthyris novamexicana. At Kingston, 9 miles | Reticulariaaff.R. cooperensis. Pseudosyrinx aff. P. gigas. west of Hillsboro, the | Athyris lamePlosa. following fossils were ?. Cliothyridina temeraria. found by Gordon: 3 I- Cliothyridina aff. C. obmaxima. Zaphrentis sp. H Cliothyridina aff. C. incrassata? Amplexus aff .A. fragilis. e Eumetria? tuta. Platycrinus sp. | Platyceras aff. P. equilatera. Fenestella sp. g Goniatites sp. Rhombopora sp. {j Al imo Orthoceras? sp. Leptaena analoga. |- Ca yon Phillipsia aff. P. peroccidens. Schizophoria aff. S. g Proetus sp. swallowi. B. Griffithides? sp. Pustula n. sp. % The crinoids were not as abundant in bed 8 Spirifer aff. S. vernon- g- .-W. fault as in bed 7. Beds 5 and 6 contain corals and ensis. -. Brachythyris aff. B. crinoids, but nothing was determined. Accord­ suborbicularis. ing to Keyes bed 5 is Devonian,1 consisting of Pseudosyrinx aff. P. three members, the lowest of which carries a gigas. Athyris lamellosa. typical late Devonian fauna. SanAndres In the exposure of Lake Valley limestone, 2 Cleiothyridina aff. C. Cannon incrassata. TO "tk I miles east of Hillsboro, Gordon 2 found beds 5 o and 6 absent and beds 7 and 8 lying on fossilifer- From limestone over- § ous Devonian shales.- The following fossils lying the Percha shale a were obtained: short distance east of hDog Canyon Cyathaxonia? sp. Kingston the writer col­ Zaphrentis sp. lected the following Amplexus aff. A. fragilis. forms, identified by Periechocrinus whitei. G. H. Girty: Rhodocrinus wortheni var. urceolatus. Fenestella, several sp. Cactocrinus multibrachiatus. Polypora sp. Escondido Leptaena analoga. Canyon Rhombopora sp. Cactocrinus proboscidialis. Cheilotrypa? sp. Steganocrinus pentagonus. Cystodictya aff. C. Platycrinus subspinosa. pustulosa. qSJ Platycrinus sp. Little AguaChiquita Physetocrinus lobatiis. In another bed were Canyon Physetocrinus copei. found the following: Fistulipora americana. Cladochonus sp. Schizophoria aff. S. swallowi. Cyathaxonia arcuata? Rhipidomella dalyana. Fenestella sp. Leptaena analoga. Polypora sp. Productus aff. P. burlingtonensis. brapfevine Rhombopora sp. Canyon Pustula n. sp. Spirifer aff. S. vernonensis. Rhipidomella? sp. Spirifer aff. S. grimesi. Productus aff. P. mesialis. Delthyris novamexicana. Delthyris? sp. Brachythyris aff. B. suborbicularis. Spiriferina sp. Cliothyridina aff. C. glen i Am. Inst. Min. Eng. Trans., vol. 39, p. 147, 1909. * Am. Jour. Sci., 4th ser., vol. 24, p. 61, 1907. 8 Idem, p. 62. 52 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1917. The fossils collected by Lee in the canyon of Triplophyllum sp. Rio Salado, on the south side of the Sierra Leptaena analoga. Schuchertella aft. Ladrones, were determined by G. H. Girty,1 S. chemungensis. as follows. All of them are lower Mssissippian Rhipidomella diminutiva? forms: Schizophoria postsriatula? Zaphrentis 2 sp. Productus gallatinensis. Granatocrinus? sp. Productella n. sp. aft. P. pyxidata. Platycranus? sp. Shumardella? aft. S. missouriensis. Rhipidomella aft. R. dubia. Brachythyris suborbicularis. Spirifer aff. S. logani. Ambocoelia levicula. Spirifer aff. S. tenuicostatus. Reticularia cooperensis. Spiriferella aff. S. neglecta. Proetus peroccidens. Athyris lamellosa. Spirifer sp. undet. Cliothyridina aff. C. obmaxima. Platyceras sp. undet. Phillipsia sp. In 1915 the writer collected from stales There are abundant fossils in the Lake Valley about 50 feet above the Fusselman ledge on the limestone in the Cooks Peak region. The fol­ north side of Alamo Canyon the following forms lowing were determined by G. H. Girty: identified by G. H. Girty: Rhombopora sp. Zaphrentis sp. Cystodictya aft. C. pustulosa. Rhipidomella dalyana. Paraparchites sp. Schizoporia? sp. Leptaena analoga. Spirifer rowleyi. RhipLdomella pulchella? Spirifer centronatus? Productus semireticulatus. Delthyris novamexicana. Productus ovatus. Composita humilis? Productus aft. P. burlingtonensis. Cliothyridina prouti? Productus aft. P. wortheni. Cliothyridina sp. Brachythyris suborbicularis? Spirifer centronatus. At the same horizon in the slope near Dog Composita humilis. Canyon were collected the following: Schizoblastus aft. S. rdemeri. From the lower division of the Fierro lime­ Dielasma sp. stone of the Silver City region Paige obtained Spirifer aft. S. grimesi. the following distinctive Mississippian forms Platyceras aft. P. fissurella. identified by G. H. Girty: Platyceras aft. P. paralius. Platyceras aff. P. equilatera. Actinocrinus copei? Dorycrinus lineatus. Lower Mississippian (Lake Valley) fcssils were collected at several localities in the San Rhipidomella aft. R. oweni. Andres Mountains. The following forms were Productus mesialis. identified by G. H. Girty: Spirifer aft. S. imbrex. Reticularia cooperensis. San Andres Canyon, in heavy ledge above Percha shale: Triplophyllum sp. Girty 2 regards the Lake Valley fauna at Schizopophoria aff. S. .swallowi. Silver City as closely related to that found at Productus aft. P. arcuatus. Fern Glen, Mo., and at other points in that Spirifer aft. S. grimesi. Spirifer centronatus. general region. Brachythyris suborbicularis. From the Kelly limestone in the Magdalena In cherty beds at top of this heavy ledge, in a canyon Range, Keyes 8 reports Batocrinus subaequalis 3 miles south of San Andres Peak: Hall. Triplophyllum sp. From the Mississippian beds in the section Spirifer aft. S. pellensis. Eumetria vera. east of Alamagordo, Girty 3 obtained the fol­ In the basal part of the first heavy ledge abovo the lowing species: Percha shale on the ridge west of the San Nicolas Spring: 1 Personal communication. Cystodectya sp. a IT. S. Geol. Survey Geol. Atlas, Silver City folio (No. i99), p. 5, 1916. Chonetes aff. C. logani. * Am. Inst. Min. Eng. Trans., vol. 39, p. 169,1909. Spirifer sp. COMPARISON OF PALEOZOIC SECTIONS IN SOUTHERN NEW MEXICO. 53

MAGDALENA GROUP. These forms are comprised in the Magdalena The representatives of the Pennsylvanian fauna in Sierra and Socorro counties. series have been studied in detail in many parts Mimbres Mountains.—At Kingston, on the of New Mexico, but the following statements east slope of the Mimbres Mountains, according refer only to the beds associated with the older to Gordon,1 the basal Magdalena strata consist formations in southern New Mexico and ad­ of about 300 feet of dark-blue and gray lime­ jacent parts of Texas. stone in thick beds with thin shale partings. Cooks Range.—About 40 feet of dark-gray The upper part of the group has about the shale lying on the white chert of the Lake Val­ same thickness and consists chiefly of blue and ley limestone high on the slopes on the north­ drab shales interstratified with several beds of west side of Cooks Peak yielded fossils that limestone from 15 to 20 feet thick. Uncon- appear to indicate the presence of a representa­ formably overlying these beds are red sand­ tive of the Magdalena group, the lowest sub­ stones and shales (Abo sandstone) of the Man- division of the Pennsylvanian series in New zano group. At the Palomas mining camp, Mexico. Possibly it occurs elsewhere in Cooks 20 miles north of Kingston and 2 miles east of Range, but at all other places visited the Gym Hermosa, the Palomas Creek canyon has and Lake Valley limestones are in immediate nearly vertical walls, the lower half of lime­ succession. The fossils in the limy layers in stone and shale in about equal amounts and the the shale include the following, all determined upper half of hard, massive gray limestone. by G. H. Girty: About halfway up the cliff a few thin beds of Derbya crassa. quartzite are interstratified with the other Chonetes mesolobus. rocks. There is no evidence on which to sepa­ Productus semireticulatus. rate the group into Sandia formation and Pustula nebraskensis? Madera limestone, as in the region farther east. Marginifera muricata. Magdalena Mountains.—In the Magdalena Pugnax sp. Spirifer cameratus. Mountains, according to Gordon,1 the basal Spirifer rockymontanus. member of the Magdalena group is 10 to 15 Ambocoelia planiconvexa. feet of moderately coarse conglomerate inter­ Aviculipecten, 2 sp. stratified with dark shale, whose bedding is Acanthopecten carbonifer. apparently parallel to that of the underlying Lima retifera. Astartella vera. Kelly limestone. This conglomerate is over­ Edmondia subtruncata. lain by 115 feet of limestone capped by coarse Phillipsia scitula. white quartzite or conglomerate in massive Silver City region.—As remarked on page 48, ledges separated by thin beds of shale. Next the upper part of the Fierro limestone of the above is a member 80 to 90 feet thick, con­ Silver City region, as defined by Paige in the sisting mostly of limestone, in which are some Silver City folio, includes beds representing thin beds of shale and quartzite. The basal more or less of the Magdalena group. The part of this member is 6 feet of thick-bedded fossils found in this upper division were deter­ drab-blue subcrystalline limestone; next above mined by Girty as follows: are 25 feet of shale and thin limestone, 2 feet Fusulina secalica. of quartzite, 50 feet of compact bluish earthy Campophyllum torquium? limestone, and 410 feet of shale and conglomer­ Zaphrentis sp. atic sandstone or quartzite. The total thick­ Chaetetes milleporaceus. ness of these beds (Sandia formation) is about Fenestella tenax. Stenopora sp. 600 feet. They are overlain by 300 to 500 feet Meekopora? sp. of limestone (Madera), more or less of whose Prismopora triangulata. surface has been removed by erosion. Productus cora. P. semireticulatus. GYM LIMESTONE. Pustula nebraskensis. Spirifer cameratus. The Manzano group is represented in central S. rockymontanus. and northern New Mexico by the Gym lime­ Squamularia perplexa. Composita eubtilita. stone, which crops out extensively in the Flor- Cliothyridina orbicularis. i U. S. Geol. Survey Prof. Paper 68, pp. 232,269,1910. 54 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1917. Ida Mountains, type locality,1 and also in the Productus semireticulatus. Victorio Mountains. In both places it lies Productus occidentalis. Productus cora. unconformably on formations from the El Marginifera splendens? Paso to the Fusselman, for the Percha shale and Pugnax utah. Lake Valley and Magdalena limestones are Squamularia perplexa. absent. In Cooks Range a thin body of the Composita perplexa. Composita subtilita. Gym limestone lies on the Lake Valley lime­ Composita mexicana? stone at most places, but on the northwest Nucula levatiformis. slope of Cooks Peak these two limestones are Nucula levatiformis var. obliqua. separated by an outlier of shale of Magdalena Manzanella eliiptica. age. The Gym limestone also appears exten­ Parallelodon politum? Pinna peracuta. sively in the Tres Hermanas Mountains, where Monopteria marian? it is uplifted and cut by porphyry, and it also Plagioglypta canna? crops out in a few small hills rising out of the Bellerophon crassus. desert in the south-central part of the county. Bellerophon majusculus? The formation has not been recognized outside Bucanopsis modesta. Pleurotomaria texana. of Luna County, although doubtless it is repre­ Rhynchomphalus obtusispira. sented in the Manzano and Hueco sections in Euomphalus aff. E. pernodosus. other areas. Chonetes playtnotus?

Gym Peak NW. SE. mf,

FIGURE 15. Section across the southern part of the Florida Mountains, Luna County, N. Mex. gr, Granite; b, Bliss sandstone; e, El Paso limestone; mf, Montoya and Fusselman limestones; g, Gym limestone with dark-gray shale member (sh). In the Florida Mountains the Gym limestone Orthonema socorroense? is about 1,000 feet thick, but, as shown in Sphaerodoma aff. S. humilis. Sphaerodoma aff. S. primigenia. figure 15, it is greatly faulted and the upper­ Bulimorpha inornata. most beds have been more or less deeply re­ moved by erosion. In Cooks Range its thick­ In the San Andres and Sacramento morn- ness is less than 50 feet. tains and farther north in New Mexico the svp- The formation consists almost entirely of posed equivalent of the Gym limestone is sepa­ light-gray limestone, mostly massive and in rated from the Magdalena group by a thick part brecciated. An 80-foot member of dark- series of red beds (Abo sandstone), but these gray shale is apparently included on the south­ beds are lacking in the southwest corner of the east slope of the Florida Mountains, but this State and also in the region near and east of may be the Percha shale overlapped, or faulted El Paso. into its present position. In the Tres Her­ Most of the fossils in the Gym limestone are manas Mountains part of the Gym limestone doubtless of the Manzano group, but they do is metamorphosed to white marble and there is not afford a basis for correlation with the rocks included a member of 50 to 60 feet of gray to of other regions, nor do they indicate how reddish quartzite. much of the group is represented here. Mr. Fossils were collected at several horizons in Girty has called the writer's attention to the the Gym limestone at numerous localities. fact that Productus occidentalis is character­ They were determined as follows by G. H. istic of the limestone capping the Sacramento Girty: Mountains at Cloudscroft, a bed which is high Echinocrinus ornatus. in the Carboniferous. Some of the gastropods Meekella mexicana? strongly suggest the Hueco fauna, and the^e- fore the formation is believed to represent part 1 Darton, N. H., Geology and underground water of Luna County, N. Hex.- U. S. Geol. Survey Bull. 618, p. 35,1916. of the Hueco limestone. COMPARISON OF PALEOZOIC SECTIONS IN SOUTHERN NEW MEXICO. 55

HTTECO LIMESTONE. widespread and not attended by folding, for the According to Richardson * the Carboniferous attitude of all the Paleozoic formations is the rocks are represented in the Franklin and same with a few slight local exceptions. Htieco mountains by a massive gray limestone The first Paleozoic event of which there is of which 3,000 feet appears, but the total thick­ evidence was the deposition of sand on beaches ness is greater, as more or less of the top has of granite and other old rocks in the later part been covered or removed by erosion. Thin of Cambrian time. There may have been bedding is rare, and chert is practically absent. accumulations of earlier Cambrian sediments, The magnesia content was found to be less than but if so they were completely removed. Pos­ 1 per cent. Locally some beds are black; in sibly sedimentation was continuous into early the Hueco Mountains most of the limestone is Ordovician time, when the materials of the El light colored. The Hueco Mountains consist Paso limestone accumulated to a thickness of mainly of this formation, and it constitutes the 900 feet or more. The hiatus between the El northwestern flank of the Franklin Mountains. Paso limestone and the Montoya is a long one, The Hueco limestone carries an abundant fauna representing all of the Middle Ordovician and regarded by Girty as of late Carboniferous age, the early part of the Upper Ordovician. The on account of which at least the upper part of it hiatus between the Montoya and Fusselman is has been tentatively correlated with the Kaibab from late Richmond to probable early Niagara limestone of northern Arizona. time. Only a small part of later Devonian time is represented by the Percha shale, so GEOLOGIC HISTORY. during that epoch there was either long emerg­ The sequence of events in southern New ence of the land or extensive removal of earlier Mexico during the earlier part of the Paleozoic Devonian sediments. During part of early era can be known only in a most general way, Carboniferous time the region was submerged for many long intervals of the time are not and the Lake Valley sediments were laid down, represented by deposits. It is probable that but there is only a long hiatus to represent later many beds were laid down that were subse­ Mississippian time. Pennsylvania!! and Per­ quently removed. Doubtless some of the beds mian time is represented in the main by deposits now remaining have been thinned by erosion, of the Magdalena and Manzano groups and the and possibly, also, they were formerly much Hueco and Gym limestones. The Hueco and more extensive. Some or all of the pre-Penn- Gym are contemporaneous, at least in part, sylvaniaii formations may have covered all of with the Manzano group, which includes 500 New Mexico. Apparently the uplifts were to 1,000 feet of red beds (Abo sandstone) that i U. S. Geol. Survey Geol. Atlas. El Paso folio (No. 166), 1909. thin out to the south. o