Monday, May 16, 2011

DSCQHR - Working Hypothesis

Sanborn Map of DSQHR dated 1897. Note location of Josephinum Orphanage and, to the immediate east, the kitchen and boys dormitory. The field to the east is the western edge of the DSCQHR excavation site.

DSCQHR Working Hypothesis:

I will be modifying this post during the course of the week with other materials but would like to advance a working hypothesis for our very interesting site along the following lines and we can see how well it holds up:

The DSCQHR artifact assemblage deposition results from preparing macadam or tarmac access road to the pumphouse and well.

On May 14th, 2001, at Trench 1A (the 1m by 5m), our team excavated the remains of a possible macadam or tarmac path of an as yet undetermined width at approximately the 10cm to 20cm level. This macadam or tarmac structure appears composed of broken stone mixed with asphaltic cement. Immediately below the approximate 10cm level of this macadam layer is what appears to be a foundation layer of compressed broken stone. Both the layer of broken stone and the layer of macadam evidence signs of having been subjected to heavy pressure, perhaps a steamroller. Our team also excavated a large piece of terracotta drainage tile as well as a possible piece of interlocking concrete curb block.

This macadam road structure is perhaps the most important feature excavated at the site to date for its presence offers a means by which a hypothesis may be advanced that explains the deposition of the assemblages we have collected so far.

The entire site at the 80m and 90m transects appears to have been leveled prior to the macadam or tarmac path construction with fill. This fill contains a significant amount of assemblage, highly fragmented and disarticulated. At first glance this fill contains artifacts datable anywhere along a range of say 1830 (for the glass trade beads) to the early twentieth century (carnival glass fragments); however, given significant number of cut nails unearthed, one may tentatively conclude that a major source for the deposition of this assemblage occurred between 1883 and 1906 (the date of the construction of the main seminary building that was to become the DSCQHR convent complex and the San Francisco Earthquake of 1906).

Photograph of artifacts found in test pit 1A, 04/30/2011,DSCQHR, level 20-30cm.

There is a large amount of white slipware with white paste that, given its sturdy utilitarian profile, suggests use in an institutional setting befitting an orphanage or school kitchen. This white slipware may be found bioturbated as surface scatter from the 0m transect through the 90m transect. Coarse red fired brick fragments are to be found in large quantities. It is known that construction materials employed at the DSCQHR complex utilized large numbers of such brick. This fill layer contains artifacts consistent with, but not necessarily exclusive to, a dormitory or kitchen building destroyed by earthquake and (or) fire circa 1906).

Detail of Sanborn map dated 1897 showing layout of Linda Vista Winery (McIver property) located to the immediate east of the DSCQHR site. The McIver mansion was destroyed by fire in Nov. 1898.

A secondary but important note should be made of the following event that occurred to the immediate east of the DSQHR site in 1895, the burning of the McIvor Mansion at the Linda Vista winery, the San Francisco Call reported the incident as follows:
Linda Vista Razed by a Conflageration
Beautiful McIver dwelling at Mission San Jose Burned with Its Contents

Mission San Jose, Nov. 8. – Linda Vista. The beautiful home of C. C. McIver was totally destroyed by fire at 8 o’clock this morning entailing a loss of $50,000, covered by $25,000 insurance. Heavy wind was blowing in nothing could be done to save the structure, although there was a good water supply. Efforts were made to save the costly furniture, but little could be rescued.

The fire started on the roof from sparks from the chimney. Mr. McIver is a wealthy winemaker of this vicinity, and his home was the finest in this end of the county. Linda Vista has been noted for its hospitality. (Source: San Francisco Call, Nov. 8th, 1898)

Many of the artifacts unearthed so far evidence signs of exposure to heat. There are several sherds of glass that appear to have metal oxide residue deposited across both obverse and reverse surfaces. Although the artifacts so far unearthed do not demonstrate a provenance from the high-end of the social scale, admixture of materials from the McIver fire should perhaps be kept in mind.

The Barber Asphalt company was one of the largest asphalt companies in the Western United States during the late 19th and early 20th century. Barber Asphalt Company largely utilized asphalt mined near Santa Barbara. It turns out that California developed a world-class asphalt product that competed favorably against materials mined in Trinidad and Bermuda (more on this later). Note the presence of concrete curb blocks, crushed rock, and asphalt road surface. The composition of the asphalt at the DSCQHR site is a bit different but utilizes similar principals on a smaller scale.

Summary: the assemblages so far recovered from the DSCQHR site suggest that an area running from north to south at the 80m and 90m transects was leveled using fill dirt containing artifacts from (a.) most likely DSCQHR convent debris resulting from the 1906 earthquake, (b.) artifacts possibly resulting from debris of the McIver Mansion fire of 1898, or (c.) fill dirt containing artifacts from both the 1906 and 1898 events. It has not yet been determined where these respective debris were originally deposited prior to use along the 80m and 90m transects. Their location at the present excavation site is in all likelihood a secondary deposition related to construction of the well access road.

The fill containing the 1898-1906 horizon materials served to provide a level grade necessary to receive the crushed rock foundation and the superposed macadam or tarmac road surface. The purpose of this road surface was to provide access for drilling and maintaining the well, pumphouse, and irrigation system envisioned for the agricultural operation of the DSCQHR orchard and farm assets in the first half of the 20th century.

The type of asphalt system utilized at the DSQHR site began to fall out of favor with civil engineers for use in main public roads about 1911. Its presence on a private access road, however, could have continued into the 1920s.


  1. Great work David! I have ArcGIS software that we can rubber sheet these maps onto a layer with. I still need to get the gps data from the other David. Has anyone found aerial photos?

  2. David, could you be our guru for research techniques? Amazing, the stuff you've found.

  3. David, what a fascinating read! Your historical research is really bringing our little patch of land to life. My crew over at CU2 was also finding huge chunks of asphalt last week; it's great to have some potential context for it! Thanks for all your meticulous research, and for your detailed blog posts. Yay history! :)

  4. David,

    Thank you for you amazing research! Over at CU 3 at about 20cm in our Level 2-Level 3 we are uncovering a large chunk of possible concrete curb block and we have also found many chunks of asphalt and burned glass!

  5. Hello All - thank you very much for the input. Remember, the hypothesis is out there to get kicked around against the archaeological evidence. This is only a first crack at a difficult (for me)site and context.

    I had posted without being able to modify the draft; there is an error message present when one attempts to edit posts - so the additional data I intended to weave into the narrative outline will have to wait.

    Kristen - you are quite correct with respect to the depth of the asphalt (macadam) layer. My post should read 10cm-20cm with the asphalt present toward 20cm. It would be nice to dial this layer in across the site as we may be able to date this against the DSQHR records and generate a stratigraphic benchmark.

    Basically, the hypothesis seeks to explain the fragmented hodgepodge of artifact layers resulting from use of debris-saturated soil as fill for a small asphalt access path or road.

    One of the major problems is my supposition that this asphalt structure is a road or path. The supposition is based on the feature coming to light in at least two of our units at a similar level apparently on a line with the well.

    Having taken some time surveying and walking the well site (outside of our area), I am not certain the asphalt extends that far south.

    A second major concern: we appear to have fill containing artifacts above and below the asphalt feature - this needs to be sorted out carefully.

    As to historical data - it is intriguing, but not definitive as our site lay between DSCQHR and the Linda Vista Winery 1/4 mile east of town. The mansion that burned is not marked on the Sanborn map (curiously). No repository seems to possess exact data on its location.

    The Asphalt and Fill hypothesis raises as many questions as it purports to answer - all I can say is that we know there was a dance, but we can not yet call either the tune or the steps.

    I look forward to further input from the team.


Feel free to comment on what you see & read here!