7,g ARCHAEOLOGY OF CCO-137, TM- " CO~NCORD Mi.'ANI" SITE Robert Fe Heizer Introduction In Aujust, 194h6, Mirs. Robert Enge of 21 Gregory Lane, Concord, Califorl-nia assivtozed by h-ier neig'fhbor, Mrs. Al Stone, be-7an dig-ing a nit in her back yard w-hich was to become a svrinmming pool. At a depth of 5 feet from '.-he surface they encountered 2 human burials, and reported thlese to thae Contra Costa Countyr Coroner, Dr. C.L.Abboott, --i.Do. The coronier examined the remains, and iw-ith Dr. "., Thomz.Z;.pson` his autopsy surgeon, wrte a very credit-able report on bhe bones, concludCinc' that -thes ree-relsonted those of Indiaens and -orerc to be attributed consiCerable '?C jur.-wt from the depth at which they w-ere foun.d. Dr. Ab'bo-t releacascd the I eotal 1 ateriLal to tihe University of California Lluseuil of Ani':ltf10,000 years 7 SCHEMATIC ILLUSTRATION OF THE PROBABLE RATE OF PROFILE DEVELOPMENT WITH PERIODS OF TIDE. Particularly "designed" for environmental conditions comparable to those at the Concord Site (CCo-137.) 0 - - -- - Ai N Pit B I' A Swimming pool pit I I i I I I I i I 0'I I. I I I i I IA L Pit A I Datum B, west of Datum A. 69 t I .q- C F H A 12Y7 /1/Al PLAN OF EXCAVATIONS AT CCo-137. Scale: 1 inch equals 8 feet. FIGURE 1 w m C+ ct, tu ~i b> Fo CD 01 0 n t-b I 0 CA 0 H c. ro~ (D GO r: ct 0 Tsaroi Location of Site CCo-137. The site lies 315 miles north of the town of Walnut Creek at an elevation of 50 feet above sea level just east of a branch of Grayson Creek and .5 mile west of Walnut Creek, a somewhat larger stream which flows north, in a deep and narrow trench, to empty into the marshy shore of Suisun Bay some lo miles beyond, The Ignacio Valley, whose main drain is Walnut Creek, is from 2 to 4 miles wide and 8 miles long, and site CCo-137 lies at about its center toward the western edge - Stratigyraphy arid Cultural Deposit As may be seen in Figs. 2 and 3, the habitation level formed a continuous stratum avera-;ing- about lhg inches in thickcness, Althougflh its uppe2 surface and lower surface were somewhat irregular, this stratum lay in an approximate level plane. The irregularities of the surface of this stratum may be in part dylue to degradlation or erosion, and its uneven bottom is almost certainly ascribable to disturbance of the sUbsoiL by the occupants of the siteo Burials, for exanmnple, usually lay in graves filled with refuse deposit andll excavated into the subsoil, The stratigraphic profiles shown in Figs0 2, and 3 would indicate that th-e original surface upon which the refuse accumulated was slightly irregular, and the culture level more or less followed the dips and rises of the original surface. The buried habitation layer has been traced by Mir. Boyd and Mro Cole 125t northwest, 401 east, and 55' west of the center of the swimming pools The habitation level consisted of a dark colored earth containing fire-cracked stones (evidencing the stone-boiling of foods), bones of food animals (see list of species infra),, discarded marine and freshwater mollusk shells (see list of species infra), finely divided charcoal and ash, and the like -- it was, in brief, a typical Californian midden deposit. 3 Lying over the occupational level was a deposit iX8 inches thick of naturally, laid alluvial soil which, accordint to thzle opinion of Storie and tTarraCdine (see their report infra), took a lon- time to be deposited, and at least as miuch additional Ye -to develop a semi-mature profile. Fig, 4 indicates that the final occupation of thle sate (4h1h-h6tt level) followed a brief period of flooding as evidenced by the silt deposition at 46" to h8" lying upon the main occupation deposit. Storne and Irarr-adine speak of "gponded sediiments." Allyrn G. Smith and G. D. Hianza of the California Academy of Sciences hCAve identified in the alluvial soil above the culture level the shells of Anodonta, Pisidium occidenatale Newcomb, Planorbis vermicularis Gould, He'lisoma tenue Philippi, and Lymnaea disidiosa Say, pointing out that this assemblage would normally occur in a freshwater lake, It is difficult to envisage a lake occupying Ignacio Valley with the present topography. The present surface of the site lies at 50 feet above sea level, and 20 feet above the present level of VEalnut Creeko The valley surface on the bank of wralnut Creek is about 8 feet below the surface of the CCo-137 occupation level. That consider- able alluvial deposition has occurred in the floo-pelcin of the creek is shown by the C.discovery within one mile of CCo-137 at site CCo-135 of occupation levels in the ,iokelimmne aqueduct cut into the 7.1alnut Cree.k floodpLain sedir.lents at a dcpt. of 6 feet fom thesurface. A second nearby discoveCny was made at site CCo-133 of a huran sikeleton lying at a dcept.h of 5 feet froia the surf ace and. covered with undisturbed alluvial soilo. These would ind'icate a general deposition in the Ig-nacio Valley of alluvium follovfing an early occupation by man. I have been unable to secure from any geologist, geogrrapher or physic- ,rapher any coher renzt or convincing reconstruction of thae events and chan-;es wh-iic h imust have occurred if the alluvial soils capping, the culture stratu at CCo-137, the hearths at CCo-135', and the skeleton at CCo-133 were laid doiwn in a body of water, Perhaps thiey are the bottom sedliments of lakes or ponds., but to my mind the probable explanation lies in assuming a gradual aggradation of outwash and overflow silts froim. the hills to the west and in the floodplain of W'alnut Creek. This deposition must hlave been fairly continuous, gradual, and covered a long period of timpe, and in the process there could have occurred local physiographic changes in terms of level due to uplift, subsidence, soil creep, alterations in thei drainage pattern, and the like. The present situation of site CCo-137 as a habitation spot for primitive ;man is not particularly favorable. Fresh water is soine distance away, the nearest being at Grayson Creek or Yilalnut Creekl, each about .5 mile distant. A former stream channel which must have carried considerable water at one time was located immediately west of the site2o. T'his channel, marked by pea- to thumb-size -ravel, lies under several f cet of alluvium anCd runs in a south-north direction. Such a stream, perhaps a former distributary of Grarson or W-ialnut Creek, ma-r in high ;water and flood, have becr. one of the sources of the sediments which nowT cover the culture level of CCo-137. The source, couf sc, and destination of this -former stream needs further investigationl The Human Remains In all, 9 human Ourials werc recovered, froma the CCo-137 habitation level, 3uri-als 1 and 2 were exc.-cated by Mrs. Enge and Mrse. Stone wrho report that thCy lay fully cxtended on the back (supine). Bur-J.ial 2 is further described as having the ricgt lower loeg crosscd ovcr the lower left, Both ladies dug the remains out carelfully after first exposing them, and we are inclined to agree that their observations are correcct, Burials 2-9 wcrc all flexed0 All lay either at or bclowr the leve;l of the habitation refuse at depths of r4 to 58 inches, Average depth of the 9 burials is 63 inches0 The grave pits were dtua from th-e shallow habitation layer into the sterile Sand base. Calculating the habeitation laN'cr at rnot less than 44" froim surface, the burial pits could have been not less that 10 or more than 24L' deep. These are average for Ccntral California sitc graves, The burials were' not concentrated, but lay isolated (nos. 6.8,9) , in ipairs (nos. 1,2;3, 5) or in greater numbers (nos, 3,495,7)@ Prohably more burials lie unexcavated south of the east-west dattun line from 35 to 50 feet west of Datum Ao - 8 - The bones are not only 'heavily %encrusted withl a calcareous accretion which can be rem-lioved by pr-yinigc wvith a krlifjlDlacie, b-t, are also heavily rmineralizod, Lvorythling about thr-e bones is reniniscent of the s'koictal material from the olCer M1iddle and Early Horizon sites of the lower Sacrai-icnto Valley, arn d quite unlike anythingF thus far noted for the San Francisco Ba-y region. Dr. T. D. LcCo-wn is preparing a report on the CCo-137 skeletal remains which wrill be publishod in a futurc number of this series, The Artifacts The dark occupational refuse stratum produced very few artifacts. We estimate that our excavation turned ovcr not more thlan 600 cubic feet of occupation refuse, arid from this we recovered only 3 actual artifacts not associated with burials. The rcenainder of the artifacts were burial accompaniments. Dissociated artifacts: A sandstone mortar rim fraient (length 8 cm., width, 35 cm.,, height 2*7 cm0) came from 50r8tg Wf/o10o1 ;T-S of Datum A. It is apparently, though not certainly because of its small size, close to tynpe Bo2 mortars of the Interior Valley, At 66t9"t W/3t6u S of Datum A came an antler tine 1315 cme long whose tip appears to be worn, It may be tentatively identified as a punch or flint flaker6 A fortuitous maimmal bonc sp.linter awl rith a sharpened tip came from Pit B. It is 5oh cm. long and leO cm. wide, Artifacts with burials: An obsidian blade 1792 cm. long, 3*1 cm. wide and 1a0 cm, thickC ,was .found on the ch.est of burial 7, One sidc is slightly convex, the othier has a suggestion of a ke-l or ridgP In sh.ap rcmatorial. and technique it is indistinguishable fro-M numerous specinmens in UCLA from Napa Valley and Lowrer Sacrame-nto Vallcy sites of Middle -Horizon times, ith Dburial 5 werc 3 shell ornaments made of grcen-backed abalone (Haliotis cracherodii.) The largest was reCl-shaped with two central perforations and measured 13 cm, long by 8.5 cm. in widtho Affixed by calcareous accretion to the convex back surface were several shell beads, ltTo rings (a pair?) of the same sh1ll from burial 7 arc 30 3 cm, in diameter and havc a oentral hole 1 cm. in diameter. They are classed as type C (1), and thc~y may be notcd as typically Middle 'Horizon in time, - - - c F I PLATE 1. BURIALS AND STRATIFICATION, SITE CCo- 137 N z 0 0 us 0 0 0 z. 0 z ~ o 0 IaJic 0 a) L-) o From three burials (nos. 1,2 ,1) caine 4 srmall 0livella biplicata shells with gTroJund-off spiros. They rangc in length from 7 to 11 mmab The almost exclu.sive use of such sm, all whole shell beads is most typical of the Early Horizon. 8 ?'wo burials (nos. 5,7) yielded '65 small round Olivella cupped disc beads 5 mm0 in diameter. They are conically drilled from the concave surface. This type of bead is most characteristic of . iddle Horizon sites, buzt also oecurs in tthe Late culture period. Burials no. 5 and 7 produced 82 flat disc beads of clamshell QLxidornus?, Macorna?) whlich are badly corroded0 TI-Ley ere conically drilled, raoge fromT6 to 9 mm. in diameter,, and appear to have been made indCivicvually rather than by the ttproduction method" l;anil.iar to the recent Indians. 9 Closoly sinilar beards are knoi,4-n irola one site (Sac-73 ) wh'Aich is M.iddle Horizon in timec; Two thin birdbone tubes or beads cane from a -rave, probably burial .no, 7, though this allocation is uncertain due to a catal.og-ue confusion. They rmeasure 225 era, long, l5 cm. (dameter. Such lbeadis occur in both coast and interior sites throug7-hout the entire span of prehistor ic occupation. EXPL ANA'NTIO N OF PLAT'LES 1 and 2. Plate 1. a, burial no. 7; b, buria[l n1o . 6; c, burial no. 4; d, burical no. 8; e, charoal lined pit 58 feet tjest of LDaturm A; f, dark occunation stratum in. northi;est corner of swinrmiing pool pit; L, so-uth wall of pool. Stake mrarks top of dark occunati on stratu~m lying under dense light col1 ored cl ay; h, southl w,,all of excavation (A-B line of Fig. 2), lower dark colore>d band is occuT)ati on stra tum; , Feature 2, cache of' large nebbloes, robabl7y cooking stones for stono-boillring, Plate 2: Contour man is ba>csed unon thre 'U. S Army DeT-r Depart- rmoent Corps of Engineers Concord Quadrangle, Grid Zone "G", 15 minute series, 1943 . Soils mnaD is baded upon the county mnap contained in EoJ. CaDr penter and SV.W.Cosby, "Soil Survey of -Contra Costa County, Cal-lifornia." U.S.Departryient of Agriculture, Series 1933, No. 26, 1939. - 10 - BURIAL S I ' SITE CC O-l 'l. Burial IJo,. 1 2.3 34 1 617 .8:9 Posture: flexed on side or back*t- X X X7'- X X X X extendec on back OGrientation _ ___ VV W WI'W V YT 'W y VT SE, A;~ . AAA1 A A IAd.A Ad Sex -___ - - - - - _ F__ I _F Iv, F P 9 T oDepti from surface (inches) 6 oo,6 6-- 6i62 64. Associated artifacts *~ ~ t Small spire-n opoped Olivella beads X X X Circular, conically drilled Olivella and Macoma disc beaCs ._._* X .X Reel -sha ped Hlaliot3 .s oLnarment X i ubcircular Maliotis d!iscs X 1iype NAb obsidian blade _ X Red paint (hematite) - . .X Animal claws ____X A, ad'ult; Ad., aCdolescent, I, infant Identifi catlion of Faunal Remains Professor R. A. Stirton identified remains of bear (Ursus colusus), raccoon (Procyon sp, ), dog or coyote (Canis spo), deer (0docoil Ts, bird, turtle, fish and various small rodents from the collection of bones dug from the buried habitation layer0. This is a representative list of food species judging from wha-t most Central Calif'ornia refuse deposits p-roduce. All are of livinLg s-pecies wh.nich occupy the regzion today or in thie recent past. At one spot waS a pile of brokA-en deer bones which may represent the disposal of the remains of a -meal or a parcel of garbage gathered from a house and buried in a shallow pit. Identification of Mollusks used for Foods From the thin habitation layer were recovered the shells of oyster (Ostrea lurida), and mussel (Mytilus edulis, Gonidea angulata, Margaritifera margaritifera,) Ostrea and Mytilus live in the saltwater bay; Gonidea andC viargaritifera coze from either a freshwater stream or pond. Ideintificat~ion of mollusks was performed by E. -H,. Gifford. In connection with the marine mollusks found at CCo-137, it is of interest to nobe soime observations made 80 years ago by ',. Blake: "Dr. Blake stated that he had been to Lafayette, Contra Costa County, to see a mound of shells. It was at a distance of about eighteen miles from the salt water, Upon examinination he found th-emn to be salt wriater shells, mussels, oysters, etc. lie further stated thcait he did not think it was the Indians who had carried them for food to that distance, as it was far, and it was not a desirable spot for such a use, and his opinion was, that the valley in the immfediate vicinity has been a salt water bay, That he intended, however, to xiiake a further exais.nation at some future time. The altitude of the mound is about ten feet, and its extent one hundred by fifty yards. There were also skleletons of Indi ans and bones of deer, etc0 , in the mouand, besides mIany flint chips's Prof. Bolander said that in iiendocino County the InTd~ns now carry mussels, etc., to still greater distances from the sea." Blake apparently changed his mind, for a a subsequent meeting it is noted that," Dr. Rlake stated, in regard to the shell mounds near Lafayette, that he had learned from an old Californian that the Indians were formerly in the habit of qathering shell fish on the coast, and carrying theim ten or fifteen miles inland for food." 11 N>o reasonable doubt can exist that the occupants of site CCo-1?7 broughlt -the oysters an(d mussels to their- villae, in the shell from the saltwater bay up the valley a few h:iles, to there open, extract and eat the meats, and discard the shells where they remain as part of the occupation re file de posit0 Chemical W Liion of Human Bone Professor S. F. Cook analyzed several sai.-plcs of ,bone from CCo-137 burials with -the following results: Organic matter 10.27 Ca 2(3a8.5 CO2 7o67 H20 41e92 The ratio of P/Co2 for the CCo-137 bone is laL9o From two Early Horizon sites to the northeast, we note the P/CO2 ratio is l,35 for SJo-142l and 143 for Sac-107. It appears that, chemically speaking, - 12 - CCo-137 is closer to the Sarly Horizon sites (SJO-142, S~j-63, Zac-107, SJo-56) thian to hLarim County Late H1orizon sites, or to Ler Sacramelnto Vall.ey- Delta MEidcdcle Hori.on sites, On. this basis alone, the si-be probablyr dates from lowrer (i.e. early) Mliddle Hiorizon timnes. Analysis of Refuse Deposit The habitation layer is a Stratum complosed la-rre].y of soil, colored black from charcoal resulbing from fires, and con-tainincg; fcod refuse in the form of mollusk shells, and animal bone0 It is strongly calcareous. Cook- afrod Treg~anza1 determained that the petrcent vf bone, by weiiht, in t he hobit- ation deposit wvas *0198 of rock, 290 .9 of' shall, .1383 of charcoal, s00130o Conclusions To the present writer, th-e cultural evidence (artifacts and burials) imneCmc..te strongly that site CCo-137 should ba classified as lidecle Horizon in tyrpe and time. In terms of years, -thoagh this is fratn:klyr a guess, should d!ata teic site as somewhere between 1500 and 35'00 years old. The md -obint ofi this rangre,9 2500 years ago or rouzhlyJr 500 D.C. sccmo not unrea-sonal,^bleo f or reasons srt forth olsehnorolt and because the pedologic report of Stonie and Harradine (infra) bears out the. concluSion of reasonablc anti-u t1,y It is admi t `ed that my ovwn es bi-ate of 2500 years and that of the suil vrerts of o a hoo ye-ar inimium is widc ly dierent, but sinc at t.i ie urosent time w-e have nlothinig be-tter than guesses to rely upon, WO Clll hove to be satisfied in conuc.inc' t -hat, in bh'-:- opi-nion of certain workerS, the it alndC its contents nay be from two t our cnnilenia old, ho. hoped that a radliocarbon (0-14) dating i be cUetcr:ineld fr i >'te, Such a date, in addition t-o rsisitin: tim rcisc timc whe n r imd H onizn c.l turLe of -Lr Central Catf1li..fornia coest -was- i Lin force 11-il of-fer evidence of th-e a,.ount of tLme reluired -o denosit a soil lCye'n .; Le~t thick, ane for t-his deposit to underg-o the c necessary pr-ofile develo{ ? rm to arrivce at what Stork anCd Harradinc call, in their report which inn' diately follows, t"semi-mUture-"t . Robert F, caiker Direlctor, TUCAS Halbit.ation Sterile adobe rn d clay overburden She-l-l Hey hsabdi ati clay -e HeI(-avy habitatiom levrel Figure 3. Stratif ication along I - J ld.ine . - I1I - NOTES ANID BIBLJOGRAPHY 1. Numbers 12-7393/th0l, UCG,. A copy of the Coroner's report is filed in the UCAS records. The cuiltural material is catalogued as follows in UCM/&: 1-68299/68324; 1-69971/69085; 1-84358/84370; Accession No. 880. 2. This site has already been mentioned in the literature by R. K. Beardsley, "Culture Sequences in Central California Archaeology." American Antiquity, 14:1-239 1948; S. F. Cook and A.E*Treganza, "The QuanGitative Investigation of Indian MoundslT UCP.AAE 40, no. 5, 1950; R. F. Heizer, "The Archaeology of Central California, I: The Early Horizon." UC-AR. 12, no, 1, 1949; K. MIacgowan, Marly Man in the Newif World. New York, 1950. 3. Cfe Cook and Treganza, Op, cit. in note 2; A. Tregcelnza and S.F.Cook, "The Quantitative Inves7flalTon of Aboriginal Sites: Complete Excaviation with Physical and Archaeological Analysis of a Single Mound.."' American Antiquity, vol. 13, pp. 287-227, 19)t8o See also S. F. Cook. "Physical Analysis as a Liethod for Investirgpating Prehistoric Habitation Sites." UCAS-R 7, Paper No. 1, pp. 2-5, 1950. 4. A begirnning of this studjr has been made by H.A.Boyd and L. Cole, "Some Age and Space Relations of the 'Concord MIan'," Ms in UCAS files. 5. Compare with C.2 Meighan, "Observations on the Efficiency of Shovel Archaeology" UCAS-R 7, Paper no, 4, pp. 15-20, 1950, table 2. 6. J.B.Lillard, R. F. Heizer and F. Fenenga. "tAn Introduction to the Archeology of Central California."' Sacramento Junior College, Dept. of 4toolo, Bulls 2, 1939, p. 90 7. Ibid. 8* R. F. Heizer, Op. cite in note 2, p. 17, 9. Cf. J. NV. Hudson "Porno W51ampum Makers", Overland Monthly 30:101-108, 197.o 10, Proc., Ca-if,* Acad. Sci. 4: 156 , 1873, 11. Tbid*2 p. 161. 12. See R. F. Heizer, Op. cit. in note 2, for a cultural analysis of these sites and the :EaIrly Horizon culture, The chemical data cited here are from S. F. Cook, "The Fossilization of IHuman Bone: Calcium, Phosphiate and Carbonate. UC-AIR, in press. 131 Cook and Treganza, Op, cit* in note 2, Tables 3,4, 14. All rock in the midden layyer was saved during excavation of the pool area, This rock consists of fire-cracked fragments from the stone-boiling of foods, The to-tal amount recovered amounted to 51 pounds, 15* Heizer, Op. Cit* in note 2., p. 39. Incidcntally, sito SJo-68, thc latest settiujmcWn kIn&mn of the Early Horizon, has rocontly boon dated by W.F.Libby, using tho radiocarbon ((Cjj1)mothod, as being 40524 160 years old. - 14 - APPENDIX I AN A-GE EJTFIT. 2 OF2LZ DLi: TAIALS UiF7A-THED 1 NEAIR CONCORD, CALF OUILI IA U, BA SED ON PEOLO)GIC OBS016ERVA.TIONTS 2 R. Earl Storie and Frank Harradine The unearthing of several human skeletons from a s-;Jflimlfllng pool excavation at the obert L-ng residence near Concord, Calif:orn ia;- afforcled an excellent op-:)ortunity for collaboration betw>J(een thc Depatrtent of Anthropolo-y and the Division of Soil's in an effort to csta'blish an approx-firimate a; e of the burials. The nature of the actual contentS of-r the burial pits adid allied data were of concern to thle anthropolo,-ists on thlu project) whereas thie viriters of this repor-lt, as soil technlogo~ists, were interested more in the nature and' seeuence of soil hiorizons and other data lying above the burial pitSo It becane evident after the first critical observations at the excavation that a "long time"t had been necessary for the parent soil material to be deposited above the burials. Also an equally long or longer time was necessary for the soil forming processes to differenttiate this soll material into horizo-ns characteristic o:f a semi-mature profile. Unfortunately there is no definite correlation boetwvreen the degree of mtaturity of soils as evidenced by horizonal characteristics and actual age in years. Only an estimate of the actual age in years of a given soil profile can be offered after the variable factors of soil forming processes are considered and correlated with logical rcasoning based on known facts of soil behavior. A schematic diagram showing the sequence of horizons of a Tierra soil profile and other strata overlying the burial pits is containecd in Fig. *. Beginning with the primary occupational zone at a dopth of 43 inches from the present erod(ed 'land surface, the sequence of events and probable tie involvod is thoug--ht by the writers of this report to be as folllows: 1. After an indefinite period of occupation at the 4g inch dceoth a relatively shiort period of flooding and rapid cdeposition of four inches of f ine sandy material was deposited, causing a temporary vacancy of occupa-tion. 2, The second, or teiinoal occupation at approximately hh inches from thle present surface was brief' ancd terininated by an invasion of poncded, or very slowly moving, wators. These waters carried very fine sandy cand silty sediments that were slowly deposited and ult.;_atc.ly built up a l^yer of parent material about lh inches deep over> the terminal occupational level. 1. Report by the Division of Soils,, University of California, Berkeley. 2, Soil Technologist and Assistant So-il Technologist, respectively (1947). (Approx. extent i .of eroded I } surf ce) 0 - Present occupation level 0 oH cd *r- E-- Final period of slow, uninter- ruptetd deposition of soil material and subsequent form- ation of a seuli-mature soil profile. Organic coloration from veget- ati ave cover during brief flood period and rapid deposition. Re-invasion of ponded waters with slow deposition of soil material resumed. Terminal occupation zone. No occupation during brief flood period mad rapid deposition. Primary occupation zone. 11 Yellowish brown clay pH 7-8 I I Browvn sandv loam. , Calcareous pH 8.2 60" It. broawn fine sandyr loam, Calcareous pH 8.0 * Bi' 'ials' * in pits . 701" FIGURE 4. SC"HEM'IATIC DIAGRAM SHOWI!NGlC SEQUENCE OF HORI iO0NS OF TIERRA SOIL PROFILE ANTD OTHER STRATA OVE.LYING BURIAL PITS. 3, Apparentlyr thje waters receded for a short time allowing the grorth ofr plants. T'his is partielly evidencd by a two inch dark colored layer of soil w.,hich presumably wvas darkened byr decayed vegctative mattcr,, 1: The final dopositional pene wa s prolably continuous, but certainly very long in durRation, The absence of stratification and fineness of the particles comprising this material., together with other criteria, lend alnmost conclusive proof that thiis last deposit was verj slowly laid clown by still w-.ters. 5- It is froia this miedium and f-ine-textured marine, depositien -that a ciaracteristic sermi-mature profile of the Tierra seri;3s has weathered, (A sketch with brief notations dcseribing tie Tierra Soil overlying the burials is contziemed in Figo 2o A more detailed series description of a typic,-l T;iJerra Coil appears at the conclusion of this report.) TIjo age of a soil is seldom cons:idered in terms of years by a soil scientistt It is -enecrally bascd on the degree andl- char.cteristics of horizontal difCerentiation which in turn cat-egorically arranges soils into five periods or stgces of Lmaturity, Two soils deriveld from id-entical parent mnaterials hut forred under different climatic and topographic conditions may not r .ach the same state of profile maturity at a Given time in years, A brief description of the Live sta;es of maturity are as follows: I. Recent profiles are without definite horizons of eluviation or illuviation; relatively unweathered recent or very imumlature solls. IIa -YOUng Pr ofiles have slighltly compacted subsoil horizons but without clay accumulations; slightly weathered immqature soils. IiIIn~maturc profiles have compact subsoil horizons with distinct clayr accumulations; moderate ly weathered imilature soils0 IVT, 2emi-macature profile->s have vary comnpact, semi-cemented horizons with high clay accumulations; strongly weathuered V. Mature profiles havc cemented, rock--like hardpan horizons or com.at and highly colloidal cl-ay horizons; fully weathelred mature soilS, An attem.,pt is made in Figure 1 (top) to graphically present the wri-ters ' thcor-ics, or estimnatcs att least, as to the rate of profilc d(e.vlonmnt in te.rmas oL years, .A, blricf s-nmati on of -the known and observable facts regarding the soil mass above the burials, together lith conclusion by inference, will foll'ow: 1, The parent, soil material ov-rlying the terminal occunational zonc was slowly deposited by ponded or slowly moving water, Fineness of material, the. absence of stratification, and occurrence of' vcry small marine shell deposits comprises the principal substantiating evidCince It is estimated to have taken from about 1000 to 3000 years for this deposition to take placc. - 16 - 2. The gencral cha7,racter of thc Tierra profile is consistent .with thu definition of a semi-mature so1. Such criteria as the dense columnar structural units in thne subsoil; concentration of li.mc in the lowvcr subsoil pDrismatic units, and rangc in pH valucs arc indicative of a lonrv poriod of leaching and profilc development. In process of soil formation to a stage of semi-m.at-urity in this Ticrra nrofile is bclirved to have taken from 3000 to 5O000 years0 This intcrval of time must be addeld to the timle already allowed for the deposition of th(e parent soil material, 3. In the writers! final analysis then, an agc estimvate of the burialls, based on pedological observations, wo-ald havo occurred between 4000 and. 8000 ycars agoO - 17 - TIEaRA SERIE7S SO:LS The Tierra serics includes dark-coloreld slig-htly acid soils dcevcloped from extrcmely compact or partly consolidated old sedimcntary deposits. These soils occur in the vallcys and coastal plains of southwesltcrn California wrhore thc mcsan annual proceipitation ra,.nges fror:i 12 to 20 inches0 They arc grasspland soils, soirvwhatU prairie-like in character. Iany areas are on concave, slopes adja1cent to dciinsgeways . They are closely associated in places with Chamise soils, which are a lighter browin and grenerally occupy slightly steeper and l'onge-r slopes at higler elevations, where the soils of the two scrics lic adjacent to each other. I. Soil Profile: (Ti.crra fine sandy loam) 1. Prill Yrayish-brown or very dar'k browvni shi-gZray 'riable, sliglhtly acid fine smlc7y loam; abort 8 incheis thick0 2> Darl-gray, darkl grayish-brovwni, or narbr blck s.andy loam -or clay loam that is plastic wvh, n weot and nard wh,,n dry, This layer is about 12 inches thick9 3. Dark-gray, dark brownish-gray, or black stiff, plastic sandy clay contuining a r.ther large proportion of coarse sand and fine gravel. This layer is about 1.3 inche s th;.i cL-k and grades to 4L Extremely compact or partly consolidnted substratum of old sedimfentary deposits that is generally more fi.rmly cemented with silica or iron in the upper part and. less cemented, though st fill of semiconsolidatcd character, at grkater depths. This -materiall occurs to a depth xcccding 6 fet. II. Variations: The heavier-textur ehSd soil types aremrnore plastic in the surface soil and have a slightly heavier andcl more plastic subsoil4 Thcy arc gcencrally darker colored in the s -rf-cc soil. In a fe w includud areas along swalbs and on foot slopes the cemedc~ntod substratum lics at a depth of 60 inches or imore, As mapped in the vicinity of Con-cord in thc Conltr:a Costa soil survey (see P10 2)), small areas of Tjicrra soilo are some-wharht eroded al ong the lowe!cr m1arg7in of- the tcrrace lands wcst of 7ralnut Crek. The surfacn soil in most of thlese bodies is clay loam and the subsoil ma.y not bc so ti Thlt and cormlpact as typ.ca1.. The parent rmatezrial and lowver subsoils frooque-ntly contain limc. The liie in the lower subseils has vrwathered from the parent material lime and concentratted through leachi ng to the lower hori i ons* - 1a - III# Topography: Upland tcrraccs, most of w-hich have boon cut by erosion into rolling or hilly rcliccf, i-iany arcas occur adjacent to drainageways in concave slopes, IV. Drainage: Surface drainage is good but the heavy impervious subsoil retards the dovnward movement of water, end, following heavy rains, the soil becorles saturated and bogcy, VO Natural Vcgetation: Under virgin conditions these soils are thickly covered with native grass and scattered trees such as oakso VIe Usc: Liany areas are used for grazing,- which is very good during winter and spring. Some areas are farmoed to barly,, granin hay, and beans, and yiclds are ffair t?-o good. VIIT Distribution: Ccntral and southwestorn California ncar the Coast Raneo. Type Location.r: Santa Yncz Area, California* Serics established: Salinas Area, California , 1925' - 19 -