Thursday, March 31, 2016

April 2016 Del Air Calendar of Events

Apr 2016 
07: General Meeting: 7:30 pm in our regular meeting room 
14: Education Outreach Event: Tarzana Elementary (see article) 
15: Education Outreach Event: Chatsworth Elementary (see article) 
16: Education Outreach Event: Lorne Street School (see article) 
21: Board Meeting: 7:30 pm at Chris Ward’s home.

General Meeting: Thursday April 07, 2016 
The meeting begins at 7:30 pm in our regular meeting room at:
Northridge United Methodist Church - 9650 Reseda Blvd, Northridge, CA 91324 Guests Are Always Welcome At Our Meetings & Events.******************************************************* 

April 2016 Program:
Presented by: Mike Havstad
Mike Havstad graduated from U.C. Santa Cruz in 1971, earning a BA degree in Earth Science. Since college he has had many interesting jobs, first working at the Tourmaline Queen Mine and their lapidary shop for 1½ years, then a 3½ year stint teaching the sciences at California Preparatory School, a private high school in Encino, California.  His last mini-career was a very rewarding and enlightening 7½ years with the Gemological Institute of America, as a photographer. Mike has an impeccable collection of meteorites. His display won 1st prize at the most recent CFMS annual show & competition. Mike is going to share with us his expertise on meteorites, a fascinating subject in the rock hounding community.
Emmy Silverman, Program Director 
Support our Hobby....Attend a Local Show

April 2 - 3: CHICO, CA
Paradise Gem & Mineral Society
Silver Dollar Fairgrounds
2357 Fair Street
Hours: 10 - 5 daily
Contact: Kevin Wright, (530) 534-8364

April 2 - 3: TORRANCE, CA
South Bay Lapidary & Mineral Society
Ken Miller Recreation Center
3341 Torrance Blvd (entrance on Madrona Ave)
Hours: Sat. 10 - 5; Sun. 10 - 4
Contact: Larry Hoskinson / Leslie Neff, (310) 318-2170

April 8 - 10: VISTA, CA
Vista Gem & Mineral Society
Antique Gas & Steam Engine Museum
2040 North Santa Fe Avenue
Hours: 9 - 5 daily
Contact: Ray Pearce, (760) 726-7570

April 9 - 10: MARIPOSA, CA
Mariposa Gem & Mineral Society
Mariposa County Fairgrounds
5005 Fairgrounds Road (south of Mariposa on Hwy49)
Hours: Sat 10 - 6; Sun 10 - 4
Contact: Martin Fodin, (209) 742-4036

April 16 - 17: SAN JOSE, CA
Santa Clara Valley Gem & Mineral Society
Santa Clara County Fairgrounds
344 Tully Road
Hours: 10 - 5 daily
Contact: June Harris, (408) 265-1422

April 16 - 17: THOUSAND OAKS, CA
Conejo Gem & Mineral Club
Borchard Park Community Center
190 Reino Road at Borchard Road
Hours: 10 - 5 daily
Contact: Robert Sankovich, (805) 494-7734

April 23 - 24: ESCONDIDO, CA
Palomar Gem & Mineral Club
California Center for the Arts
340 N. Escondido Blvd.
Hours: Sat 10 - 5; Sun 10 - 4
Contact: Gayle Hamilton, (760) 726-0131

April 23 - 24: PASO ROBLES, CA
Santa Lucia Rock Hounds
Paso Robles Event Center
2198 Riverside Ave.
Hours: Sat 10 - 5; Sun 10 – 4
Contact: Mike Judy, (805) 238-4469

Visit for more show information 
April 2016 Something of the Month: “A Brief History of Meteor Crater”

Meteor Crater is a meteorite impact crater approximately 37 miles east of Flagstaff and 18 miles west of Winslow in the northern Arizona desert. Because the United States Board on Geographic Names commonly recognizes names of natural features derived from the nearest post office, the feature acquired the name of "Meteor Crater" from the nearby post office named Meteor. The site was formerly known as the Canyon Diablo Crater and fragments of the meteorite are officially called the Canyon Diablo Meteorite. Scientists refer to the crater as Barringer Crater in honor of Daniel Barringer, who was first to suggest that it was produced by meteorite impact. The crater is privately owned by the Barringer family through their Barringer Crater Company, which proclaims it to be the "best preserved meteorite crater on Earth".

Despite its importance as a geological site, the crater is not protected as a national monument, a status that would require federal ownership. It was designated a National Natural Landmark in November 1967.

Meteor Crater lies at an elevation of about 5,710 ft above sea level. It is about 3,900 ft in diameter, some 570 ft deep and is surrounded by a rim that rises 148 ft above the surrounding plains. The center of the crater is filled with 690–790 ft of rubble lying above crater bedrock. One of the interesting features of the crater is its squared-off outline, believed to be caused by existing regional cracks in the strata at the impact site

The crater was created about 50,000 years ago during the Pleistocene epoch, when the local climate on the Colorado Plateau was much cooler and damper. The area was an open grassland dotted with woodlands inhabited by woolly mammoths and giant ground sloths. The crater was over 10,000 years old when the first humans saw it, at the earliest, 40,000 years ago.

Since the crater's formation, the rim is thought to have lost 45 to 60 feet of height at the rim crest due to natural erosion. Similarly, the basin of the crater is thought to have approximately 90 feet of additional post impact sedimentation from lake sediments and of alluvium. These erosion processes are the reason we see very few remaining craters on Earth, since many have been erased by this geological process. The relatively young age of Meteor Crater, paired with the Arizona climate, has allowed this crater to remain as we see it today. The lack of erosion that preserved the crater's shape helped lead to this being the first crater recognized as an official impact crater from a natural celestial body.

The object that excavated the crater was a nickel-iron meteorite about 160 feet across. The speed of the impact has been a subject of some debate. Modeling initially suggested that the meteorite struck at up to 45,000 mph but more recent research suggests the impact was substantially slower, at 28,600 mph. It is believed that about half of the impactor's bulk was vaporized during its descent. Impact energy has been estimated at about 10 megatons. The meteorite was mostly vaporized upon impact, leaving little in the crater.