Table 1. Summary of the collected soil samples from the JMA observatories. Color taken from Oyama and Takehara (1967).
From: Relevance of magnetic properties of soil in the magnetic observatories to geomagnetic observation
Sample | Location | Depth | Color |
|---|---|---|---|
M1 | MMB North of Variation House #2 | 0.5 | brown |
M2 | 1.1 | yellowish brown | |
M3 | MMB North of Total Forth (79F) | 0.5 | dark brown |
M4 | 1.0 | yellowish brown | |
M5 | MMB Continuous Observation House | 4.0 | mixture of transparent, grayish white and black |
K1 | KAK South of Comparison & Calibration House | 0.5 | yellowish brown |
K2 | 1.0 | olive brown | |
K3 | KAK East of Underground Variation House | 0.5 | dark brown |
K4 | 1.0 | dark brown | |
Y1 | KNY North of Underground Variation House | 0.3 | reddish black |
Y2 | 1.2 | brown | |
Y3 | 1.5 | black | |
Y4 | KNY North of Continuous Observation House | 1.4 | mixture of reddish brown and reddish black |