The scaling of columnar joints in basalt: supplementary information

by Lucas Goehring and Stephen W. Morris
(Department of Physics, University of Toronto, ON, Canada)
Submitted to J. Geophys. Res.

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Introduction

This supplemental material contains field data and field observations that were gathered in the Columbia River Basalt Group. Methods of data collection are given in the paper. Descriptions of 27 field sites are given in text01.txt, where field site names and numbers are also assigned. A table of measurements of stria height and position (when measured) is given in ts01.txt. A table of column widths is given in ts02.txt. A table of joint angles is given in ts03.txt. Finally, a table of the characteristics of wavy columns (wavelengths and wave angles) is given in ts04.txt. A summary of all measurements at all sites, which includes averages, standard deviations, and standard errors for all data sets, is given in ts05.txt.

1. text01.txt contains a description of the stratigraphy, joint patterns, and cooling history of each field site included in this study. When appropriate, details are given of colonnade thicknesses, colonnade quality (large/small columns; well-formed or blocky), and the nature of nearby structures (colonnades, entablature, vesicular lava, sediments, erosional features, etc.). A list of the measurements performed at each site is included. Sites are assigned names based on nearby geographical features, and numbered sequentially. GPS coordinates, and directions for access are provided. The GPS coordinates are used in the preparation of Figure 3.

2. ts01.txt lists the measurements of stria height that were obtained during this study. On each column face stria measurements are listed sequentially, and continuously, unless a gap is explicitly noted. These data are used in the preparation of Figures 5, 6, and 7. 2.1 Column "Column #" identifies which column any stria measurement is made on. Unless otherwise noted in file text01.txt, adjacent columns are numbered sequentially, from left to right (as facing the colonnade). When a column number is listed with a lettered suffix, it indicates a column at the same position along the cliffside, but deeper into the colonnade (eg. if column 7 is exposed, the column behind it is 7b). Column numbers are used consistently here, and in table text02.txt

2.2 Column "Face width (cm)" gives the width of the column, on which stria measurements were made.

2.3 Column "Stria 1 (cm)" gives one measurement of the height of a stria (usually made at the left-hand side of the stria).

2.4 Column "Stria 2 (cm)" gives a second measurement of the height of a stria (usually made at the center of the stria).

2.5 Column "Stria 3 (cm)" gives a third measurement of the height of a stria (usually made at the right-hand side of the stria).

2.6 Column "Average stria (cm)" gives the average of all measurements of a stria.

2.7 Column "Height above baseline (cm)" gives the position of the lower edge of each stria with respect to a baseline (the details of which are given in the header information for each site). At site 17 (McCoy Canyon North) the corresponding "Height below baseline (cm)" give s the position of the upper edge of each stria with respect to a baseline.

3. ts02.txt lists the measurements of column widths that were obtained during this study. These data were used in the preparation of Figures 4 and 5, and Table 1.

3.1 Column "Column #" identifies which column any width measurement is made on. Columns are numbered from left to right, as in ts01.txt, and share the same numbering scheme as found there. Column numbers prefaced by an R represent measurements done on pieces of columnar rubble.

3.2 Column "Edge width (cm)" gives the results of measurements of the edge (or face) width of columns. Typically only a single measurement is made of each edge. Multiple entries for a single column number indicate that several different edges were measured.

3.3 Columns "width 1 (cm)", "width 2 (cm)", and "width 3 (cm)", when used, represent the results of three measurements of each column edge width. These measurements are usually made at least 50 cm apart from each other, vertically.

4. ts03.txt lists the measurements of column joint angles that were obtained during this study. These data were used in the preparation of Table 1.

4.1 Column "Column #" identifies which column any angle measurement is made on. Columns are numbered from left to right, as in ts01.txt, and share the same numbering scheme as found there. Column numbers prefaced by an R represent measurements done on pieces of columnar rubble.

4.2 Column "Joint angle (deg.)" gives the results of measurement of the interior angle of a column at a joint (or vertex), in degrees.

5. ts04.txt lists the measurements on wavy columns that were obtained during this study. These data were used in the preparation of Table 2.

5.1 Column "Column #" identifies which column any measurement is made on. Columns are numbered from left to right, as in ts01.txt, and share the same numbering scheme as found there.

5.2 Column "1/2 wavelength (cm)" gives the distance between peaks and troughs of wavy columns, as defined in the paper, and in Figure 8. This is half the wavelength cited in Table 2.

5.3 Column "kink angle (deg.)" gives the interior angle between two adjacent faces of a wavy column, as defined in Figure 8(e), in degrees. This is the angle zeta cited in Table 2.

6. ts05.txt summarizes the main results of this paper in tabular form, and includes average values, standard deviations, and standard errors for all data sets presented in tables ts01.txt to ts04.txt. It also includes the observations that underly statistical tests mentioned in the paper.

6.1 Column "Site #" lists the identifying number of each site, as enumerated in text01.txt.

6.2 Column "Site name" lists the identifying name of each site, as given in text01.txt.

6.3 Columns labeled "Error" list the standard error on the measurement to their immediate left, in the same units (if any).

6.4.1 Column "# striae measured" lists the number of different striae measured at each site.

6.4.2 Column "Avg. stria height" gives the average height of the stria measurements from each site in cm. In the paper, this is indicated as bracket< s bracket>.

6.4.3 Column "Std. dev. of 3 meas." gives the average standard deviation across the three measurements of stria (columns "stria 1", "stria 2", and "stria 3" of ts01.txt), and is thus a measure of the average difference in stria height across the width of the stria, in cm.

6.4.4 Column "Stria std. dev." gives the standard deviation of the distribution of stria heights at each site, in cm. In the paper, this is indicated by sigma_s.

6.4.5 Column "Cov/Avg^2" lists the covariance Cov(s_n,s_{n+1}), as defined in the paper, divided by the mean value (column "Avg. stria height") squared, in order to non-dimensionalize the result. Only sites where more than 20 sequential stria measurements were made, and where measurements could be confirmed to be more than a few meters distant from a flow margin, are listed.

6.5.1 Column "# edges measured" lists the number of different edges measured at each site.

6.5.2 Column "Avg. edge width" gives the average width of the column edges that were measured at each site, in cm. In the paper this is indicated by .

6.5.3 Column "Edge std. dev." gives the standard deviation of the distribution of edge widths at each site, in cm. In the paper, this is indicated by sigma_w.

6.5.4 Column "Variance" gives the ratio of columns "Avg. edge width" to "Edge std. dev." (/sigma_w).

6.6.1 Column "# angles measured" lists the number of different joint angles that were measured at each site.

6.6.2 Column "Avg. joint angle" gives the average of the joint angles that were measured at each site, in degrees. In the paper, this is indicated by the symbol theta.

6.6.2 Column "Angle std. dev." gives the standard deviation of the distribution of joint angles at each site, in degrees. In the paper, this is indicated by sigma_theta.

6.7.1 Column "# waves measured" lists the number of half-wavelengths of wavy columns that were measured at each site.

6.7.2 Column "Avg. half-wavelength" gives the average of the wavy column half-wavelengths that were measured at each site, in cm. In the paper, this is half the value symbolized by zeta.

6.7.3 Column "# angles measured" lists the number of wavy column angles measured at each site, in degrees (see Fig. 8(e) for a definition of this angle). In the paper, this angle is indicated by the symbol phi.

6.7.4 Column "Avg. wavy angles" gives the average of the wavy column angles that were measured at each site, in degrees. In the paper, this is indicated by sigma_phi.