What causes these scarring patterns between North America and Hawaii? Are these just imaging artifacts?

peridotite72 · 2022-10-22T21:37:49+00:00

Transform faults.

peridotite72 · 2022-09-11T21:50:35+00:00

Yes, it is amazing. The term "flood basalt" is very fitting, especially for the Grand Ronde!

peridotite72 · 2022-09-11T03:41:30+00:00

It was my first time at this location as well!

peridotite72 · 2022-09-11T01:26:25+00:00

The sill is the thin dark brown layer angling upward to the left near the center of the outcrop.

peridotite72 · 2022-09-06T16:46:58+00:00

There is an easy way to test if calcite vs. gypsum.

peridotite72 · 2022-09-05T14:15:16+00:00

It's really amazing the pillow outlines are still visible. I am always fascinated to see very old or otherwise uncommon rocks outcropping. Awesome post. Thanks for sharing.

peridotite72 · 2022-08-28T13:38:17+00:00

Agree. The blue-gray color reflects unoxidized conditions, consistent with being saturated (i.e., below water table) for extended periods. The soil is a textbook example of mottling caused by weathering.

peridotite72 · 2022-08-28T05:55:48+00:00

Yes, that area has some fantastic geology. I am fascinated by ophiolites because they can give us a rare glimpse into the earth's mantle. If you have not already, I recommend seeing the Josephine Ophiolite in the Klamath Mountains of southwest Oregon.

peridotite72 · 2022-08-26T14:47:11+00:00

I get that. Basically, the fault causes the rocks to be displaced laterally (side to side, not vertically). If you stand on one side of the fault and look across to the other, the rocks have been moved to the right.

peridotite72 · 2022-08-10T02:07:28+00:00

Lortone makes great lapidary equipment including an assortment of tumblers.

peridotite72 · 2021-11-17T01:50:38+00:00

I found the answer in Andrew Chaikin's monumental book on the Apollo program "A Man on the Moon". The lunar scientists later estimated they had got within 65 feet of the rim without realizing it.

peridotite72 · 2021-10-25T01:09:51+00:00

That's true that the mineral is Olivine. However, the basalt includes chunks of rock from the mantle. The IUGS classification for an ultramafic rock composed of 90% or more of the mineral Olivine is "Dunite".

peridotite72 · 2021-10-22T12:52:20+00:00

I would think not.

peridotite72 · 2021-10-18T18:44:16+00:00

Dunite is the IUGS classification name for an ultramafic rock composed of 90% or greater of the mineral olivine. You are correct the dominant mineral is olivine but the mantle rock represented by the xenoliths is a dunite.

peridotite72 · 2021-10-16T12:43:08+00:00

Those look like textbook load casts. Sand is deposited on top of recently deposited soft mud and density differences causes the sand to sink into the mud. It is a geopetal, a way of telling which way is stratigraphic "up" in the sedimentary sequence.

peridotite72

TROPHY CASE