The Sixth Seal

As I had noted in an earlier piece:

The basic structure of the vision is chronological. After seeing the Father and the Son in heaven (Rev. 4–5), the vision of the history and destiny of the world begin to unfold for John. He sees the first five seals (or first five thousand years of history) in rapid-fire, encapsulated form. Then he sees the opening of the sixth seal, which includes the restoration of the gospel. (See Rev. 6:12–7:17.)

(Full article). The opening of the Sixth Seal is described thus:

12 And I beheld when he had opened the sixth seal, and, lo, there was a great earthquake; and the sun became black as sackcloth of hair, and the moon became as blood;

13 And the stars of heaven fell unto the earth, even as a fig tree casteth her untimely figs, when she is shaken of a mighty wind.

14 And the heaven departed as a scroll when it is rolled together; and every mountain and island were moved out of their places.

15 And the kings of the earth, and the great men, and the rich men, and the chief captains, and the mighty men, and every bondman, and every free man, hid themselves in the dens and in the rocks of the mountains;

16 And said to the mountains and rocks, Fall on us, and hide us from the face of him that sitteth on the throne, and from the wrath of the Lamb:

17 For the great day of his wrath is come; and who shall be able to stand?

 (Link). (Note: Joseph Smith has indicated that verse 14 should read: "And the heavens opened as a scroll is opened when it is rolled together; and every mountain, and island, was moved out of its place." This indicates that the heavens, which had theretofore been closed due to the apostasy, see 2 Thes. 2:2-3, would again be opened).

There are four significant events: (i) the restoration of the gospel (Rev. 6:14; see also D&C 88:84-88); (ii) the gathering of Israel (Rev. 7:1-3; see also D&C 77:8-10); (iii) the sealing of the 144,000 (Rev. 7:4-8); and (iv) a great earthquake(s) and other natural disasters (Rev. 6:12-17; see also D&C 88:87-91). Section 88 indicates that this great earthquake will be "after your testimony" and sometime yet in our future. (D&C 88:87-88).

The 20th Century was actually fairly quiet geologically speaking. So, it is interesting to read about what a really large earthquake, both in terms of force and scope, can do. I came across this description of the New Madrid Earthquake:

The New Madrid earthquakes were the biggest earthquakes in American history. They occurred in the central Mississippi Valley, but were felt as far away as New York City, Boston, Montreal, and Washington D. C. President James Madison and his wife Dolly felt them in the White House. Church bells rang in Boston. From December 16, 1811 through March of 1812 there were over 2,000 earthquakes in the central Midwest, and between 6,000-10,000 earthquakes in the Bootheel of Missouri where New Madrid is located near the junction of the Ohio and Mississippi Rivers. In the known history of the world, no other earthquakes have lasted so long or produced so much evidence of damage as the New Madrid earthquakes. Three of the earthquakes are on the list of America’s top earthquakes: the first one on December 16, 1811, a magnitude of 8.1 on the Richter scale; the second on January 23, 1812, at 7.8; and the third on February 7, 1812, at as much as 8.8 magnitude.

The Mississippi Ran Backwards
After the February 7th earthquake, boatmen reported that the Mississippi actually ran backwards for several hours. The force of the land upheaval 15 miles south of New Madrid created Reelfoot lake, drowned the inhabitants of an Indian village; turned the river against itself to flow backwards; devastated thousands of acres of virgin forest; and created two temporary waterfalls in the Mississippi. Boatmen on flatboats actually survived this experience and lived to tell the tale.

Getting Over Cracks
As the general area experienced more than 2,000 earthquakes in five months, people discovered that most of crevices opening up during an earthquake ran from north to south, and when the earth began moving, they would chop down trees in an east- west direction and hold on using the tree as a bridge. There were “missing people” who were most likely swallowed up by the earth. Some earthquake fissures were as long as five miles.

Earthquake Phenonema
Sand Boils
The world’s largest sand boil was created by the New Madrid earthquake. It is 1.4 miles long and 136 acres in extent, located in the Bootheel of Missouri, about 8 miles west of Hayti, Missouri. Locals call it “The Beach.” Other, much smaller, sand boils are found throughout the area.

Seismic Tar Balls
Small pellets up to golf ball sized tar balls are found in sand boils and fissures. They are petroleum that has been solidified, or “petroliferous nodules.”

Earthquake Lights
Lights flashed from the ground, caused by quartz crystals being squeezed. The phenomena is called “seismoluminescence.”

Warm Water
Water thrown up by an earthquake was lukewarm. It is speculated that the shaking caused the water to heat up and/or quartz light heated the water.

Earthquake Smog
The skies turned dark during the earthquakes, so dark that lighted lamps didn’t help. The air smelled bad, and it was hard to breathe. It is speculated that it was smog containing dust particles caused by the eruption of warm water into cold air.

Loud Thunder
Sounds of distant thunder and loud explosions accompanied the earthquakes.

Animal Warnings
People reported strange behavior by animals before the earthquakes. They were nervous and excited. Domestic animals became wild, and wild animals became tame. Snakes came out of the ground from hibernation. Flocks of ducks and geese landed near people.

That article also describes the voyage of the first steamship on the Mississippi which, by coincidence, was at the same time:

The first steamboat travel on the Ohio and Mississippi Rivers took place during the New Madrid earthquakes. The New Orleans set out from Pittsburgh on October 20, 1811 bound for New Orleans. Captain Nicholas Roosevelt had brought along his young wife, their 2 year old daughter, and a Labrador dog. Ten days after leaving Pittsburgh, his wife Lydia gave birth to a son in Louisville, Kentucky. They waited a while for her to recover, and for the water to rise prior to crossing the dangerous waters and coral reef at the Falls of the Ohio. On the night before the day of the earthquake, December 16th, the steamboat was anchored near Owensboro, Kentucky, about 200 miles east of New Madrid, Missouri. Their dog, Tiger, insisted on staying in the cabin with them instead of sleeping on the deck. Without realizing it, they were heading straight towards the epicenter of the greatest earthquake in American history. Their steamboat, intended to be an advertisement for steam travel, was thought instead to be the cause of the earthquake by many who saw it. At Henderson, Kentucky, where no chimneys were left standing, they stopped to visit their friends, the painter John James Audubon and his wife Lucy. Floating in the middle of the Ohio River they were protected from the earthquake tremors shaking the land, but not from the hazards of falling trees, disappearing islands, and collapsing river banks. After entering Indian Territory on December 18th, they were chased by Indians who figured the “fire canoe” had caused the earthquake, but they managed to escape capture by outrunning them. They even had a small cabin fire that night which they managed to put out. Thousands of trees were floating on the waters of the Mississippi as they approached New Madrid on December 19th, three days after the earthquake. They found that the town of New Madrid had been destroyed. They didn’t dare to stop and pick up a few survivors, for fear of being overrun, and they were without supplies. Most alarming was the fact that they had not seen a boat ascending the river in three days. They saw wrecked and abandoned boats. It was undoubtedly a miracle that they survived and kept on going. They tied up at one island, and the island sank during the night. Their dog, Tiger, alerted them to oncoming tremors. On December 22nd, they encountered the British naturalist John Bradbury on a boat at the mouth of the St. Francis River, who told them the town of Big Prairie was gone. They arrived at Natchez, Mississippi on December 30th and celebrated the first marriage aboard a steamboat on December 31st, when the steamboat engineer married Lydia’s maid. They arrived at New Orleans on January 10th, 1812, safe and sound, after traveling 1,900 miles from Pittsburgh on the first steamboat to travel the western waters.