Borehole Log Maker — Strip Logs from a Spreadsheet

How to read the log below

Depth increases downward and is given in metres below ground level, ticked every half metre and labelled every metre. Where a collar elevation is supplied, a second column gives the reduced level — collar minus depth — because a correlation between holes on a sloping site has to be made on levels, not on depths.

The hatch patterns follow the FGDC lithologic standard: open clasts for gravel, a fine stipple for sand, short vertical dashes for silt, continuous horizontal rules for clay, tussocks for organic soils and peat, cross-hatch for made ground, brick coursing for rock. The USCS modifier letters compose the way the classification itself does — GM is the gravel clasts with the silt dashes added, SC is the sand stipple with the clay rules — so a silty sand still reads as a sand first. There is no colour anywhere: the figure has to survive being photocopied into an appendix, so every distinction is carried by shape and density instead.

The inverted triangle on the depth scale is the water strike, with a dashed line carried across the strata so there is no doubt which unit it fell in. Gaps in your interval table are not treated as mistakes — they are drawn as no-recovery zones and noted, because a core that came back short is a fact about the ground rather than a typo. Overlapping intervals *are* flagged, on the drawing itself, naming both rows: an exported log that quietly contradicts itself is far worse than one that says so.

Who this is for

Geotechnical consultants producing factual and interpretative ground investigation reports. Engineering geologists logging cable percussion, rotary and window sample holes. Environmental consultants logging trial pits for a contaminated land assessment. Small consultancies and sole practitioners most of all: the incumbent tools — gINT, LogPlot and their equivalents — are database platforms sold on annual licences, and on a job with six holes and no laboratory schedule to manage, most of that platform is overhead you pay for and never open.

This is not a replacement for those systems and does not pretend to be one. There is no project database, no AGS import, no lab-schedule management, no multi-hole section drawing. What it does is the part most people need most often: take a table of intervals and produce one correct, printable log sheet, with no installation, no licence server and no upload.

Honest limits

Metres only in this version. Feet are not supported and will not be faked — a log labelled in metres that carries feet is a genuinely dangerous document, and doing the conversion by halves is worse than not doing it at all. One hole per figure, one description per interval, and SPT reported as a single N-value rather than as the individual 75 mm increments. The graphic follows the first symbol of a dual classification while the symbol column prints exactly what you typed, so SP-SM stays SP-SM in the record and hatches as sand.

Everything runs in this browser tab. No borehole record is uploaded anywhere, which for pre-planning site data on a live acquisition is usually the whole question.

Common questions

The page says Pro — what can I actually do for free?

Everything except enter your own data. The log below is the finished tool running live on a real sample borehole: change the vertical scale, turn columns on and off, edit the title block, and export the figure as SVG or PNG (watermarked, like every free export on this site). What Pro buys is the right to replace the sample intervals with yours. There is no trial timer and no account, and the demo does not expire.

Which USCS symbols are supported?

All fifteen ASTM D2487 group symbols — GW, GP, GM, GC, SW, SP, SM, SC, ML, CL, OL, MH, CH, OH and PT — plus FILL, TOPSOIL and ROCK, which are not USCS but which every real log needs. Dual symbols such as SP-SM or CL/ML are accepted: the hatch follows the dominant first symbol and the symbol column prints the pair as you typed it.

Where do the hatch patterns come from?

The FGDC Digital Cartographic Standard for Geologic Map Symbolization (FGDC-STD-013-2006), section 37 — the USGS lithologic pattern set, and the same family gINT and LogPlot ship by default. The group symbols themselves follow ASTM D2487. Both are cited in the figure footer so a reviewer can check them.

Can I log a trial pit or a window sample hole?

Yes. Nothing in the model is specific to a borehole — it is a depth-interval log. Change the borehole ID to a pit reference and the method field to suit; the depth scale, hatching and descriptions work the same way for a 3 m pit as for a 30 m hole.

What happens if my intervals have gaps or overlaps?

A gap is drawn as a no-recovery zone and listed as a note — that is a real logging outcome, not an error. An overlap is flagged as a warning printed on the figure itself, naming both rows, and the log is still drawn, so you can see where the problem is instead of staring at a blank sheet.

Can I get feet instead of metres?

Not in this version, and the footer says so on every figure. Supporting both properly means a unit on every depth-bearing field and a conversion at the axis; shipping half of that would produce logs labelled in metres that carry feet, which is the kind of defect that ends up in a foundation design.