The following table lists the cooling time of lava at 5 depths from an initial temperature of 1100 deg F to 750 deg.
| Lava Depth (m) | Cooling Time |
|---|---|
| 1 | 12 days |
| 10 | 3 years |
| 100 | 300 years |
| 1,000 | 30,000 years |
| 10,000 | 3,000,000 years |
Reference
Daly 1933,
Igneous Rocks And The Depths Of The Earth, McGraw-Hill, New York.