[vc_row css=”.vc_custom_1646974268698{padding-top: 20px !important;padding-bottom: 20px !important;background-color: #6b6b6b !important;}”][vc_column][vc_custom_heading text=”Banded Iron Formation” font_container=”tag:h2|text_align:center|color:%23eaeaea” use_theme_fonts=”yes” css_animation=”flipInX”][/vc_column][/vc_row][vc_row][vc_column][vc_empty_space][vc_single_image image=”2274″ img_size=”full” alignment=”center”][vc_column_text]
2.2 billion years old
Negaunee Iron Formation
Marquette County, Michigan
This is a specimen of Banded Iron Formation (BIF) from an old iron mine in the Upper Peninsula of Michigan. BIFs are distinctive geological rock formations that hold crucial insights into Earth’s ancient history and the evolution of its atmosphere. These formations are composed of alternating layers of iron-rich minerals, predominantly hematite or magnetite, and silica-rich minerals, often chert or quartz. BIFs exhibit a unique banded appearance, with alternating bands of contrasting colors and textures as you see here.[/vc_column_text][vc_single_image image=”2277″ img_size=”full” alignment=”center”][vc_single_image image=”2281″ img_size=”full” alignment=”center”][/vc_column][/vc_row][vc_row][vc_column width=”1/2″][vc_single_image image=”2282″ img_size=”full” alignment=”center”][/vc_column][vc_column width=”1/2″][vc_column_text]BIFs are of paramount significance as they provide a record of the dramatic changes that occurred on Earth billions of years ago. These formations primarily originated during the Precambrian time, dating back over 2.5 billion years, making them some of the oldest rocks on the planet. The alternating iron-rich and silica-rich layers are a result of cyclic changes in environmental conditions coupled with formation of stromatolites, structures formed by colonizing bacteria.[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=”1/2″][vc_column_text]BIFs are a window into the distant past, specifically the period known as the Great Oxygenation Event. This event marked the point when oxygen levels in Earth’s atmosphere began to rise significantly due to the emergence of photosynthetic organisms – especially stromatolites. As they released oxygen, it reacted with dissolved iron in the surrounding ocean water, forming insoluble iron oxides that settled and accumulated in layers of iron-rich mud, eventually turning into BIF.
Beyond their scientific importance, BIFs also have economic significance. They serve as a primary source of iron ore. Mining BIFs has played a pivotal role in the development of the Iron Ranges in Minnesota, Wisconsin, and Michigan.[/vc_column_text][/vc_column][vc_column width=”1/2″][vc_single_image image=”2288″ img_size=”full” alignment=”center”][/vc_column][/vc_row][vc_row][vc_column][vc_single_image image=”2289″ img_size=”full” alignment=”center”][/vc_column][/vc_row][vc_row][vc_column width=”1/2″][vc_single_image image=”2292″ img_size=”full” alignment=”center”][vc_single_image image=”2294″ img_size=”full” alignment=”center”][/vc_column][vc_column width=”1/2″][vc_single_image image=”2293″ img_size=”full” alignment=”center”][vc_single_image image=”2295″ img_size=”full” alignment=”center”][/vc_column][/vc_row][vc_row css=”.vc_custom_1646976291797{padding-bottom: 40px !important;background-color: #6b6b6b !important;}”][vc_column][vc_column_text]
[/vc_column_text][/vc_column][/vc_row]
[vc_row css=”.vc_custom_1646974268698{padding-top: 20px !important;padding-bottom: 20px !important;background-color: #6b6b6b !important;}”][vc_column][vc_custom_heading text=”Agatized Coral” font_container=”tag:h2|text_align:center|color:%23eaeaea” use_theme_fonts=”yes” css_animation=”flipInX”][/vc_column][/vc_row][vc_row][vc_column][vc_empty_space][vc_single_image image=”2163″ img_size=”full” alignment=”center”][vc_column_text]
These beautiful agatized fossils are found in the dark depths of a root beer-colored river deep in the wilds of south Georgia. We have been diving and exploring this
river since the early 1970s. No one knows this location or the regional geology better.
In early 2021 we made several expeditions to southern Georgia and excavated some fine specimens of this rare fossil occurrence. Since that time, we have been cleaning, preparing and studying the material we found. This rare and unusual type of fossilization starts when coral heads have become buried deep in sediments. Under heat and pressure, the original coral begins to dissolve away. For reasons not fully understood, in some cases the dissolving process stopped before the coral itself had disappeared completely. In these instances, there were hollow areas inside the old coral heads that later became coated with micro-crystalline quartz – agate.
In some cases, the agatization process continued and the entire cavity became filled. In other, rarer instances, the head remained hollow with the agate simply coating the inside. This results in relic structures of the coral becoming encased in amber-colored agate. “Agatized Coral” is an often-misused phrase applied to nearly any coral which contains quartz in its replacement. Such corals are found in various strata and are known from several locations and ages around the world. However, there are only two places where large, truly-agatized, hollow specimens of this type are found: One is in certain water channels of Tampa Bay, the other is in southern Georgia. In both locations finding choice specimens has become exceedingly difficult.
[/vc_column_text][vc_column_text]
[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width=”1/2″][vc_column_text]Scientific Name:
Mineralization:
Rock Unit:
Geologic Age:
Site Location:
Excavation Date:
Excavated By:[/vc_column_text][/vc_column][vc_column width=”1/2″][vc_column_text]Cnidaria, Montastrea, and other species
quartz, variety agate
Suwanee Limestone
Oligocene, 30 million years
Lowndes County, Georgia
Ongoing since 1972
Jon Kramer, Julie Martinez, and associates[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column][vc_separator color=”black” style=”shadow” border_width=”4″ css=”.vc_custom_1646972696374{margin-bottom: 20px !important;}”][vc_column_text]
December 2021 – Research expedition with Jon, Julie and George Hecht. Paddled ten miles of the river, mapping potential sites to investigate later.[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column][vc_single_image image=”2167″ img_size=”full” add_caption=”yes” alignment=”center”][vc_single_image image=”2171″ img_size=”full” add_caption=”yes” alignment=”center”][vc_single_image image=”2172″ img_size=”full” add_caption=”yes” alignment=”center”][/vc_column][/vc_row][vc_row][vc_column][vc_separator color=”black” style=”shadow” border_width=”4″ css=”.vc_custom_1646972696374{margin-bottom: 20px !important;}”][vc_column_text]
December 1973 – One of the first Kramer Family road trips to collect agatized coral in Georgia.
[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column][vc_single_image image=”2112″ img_size=”full” add_caption=”yes” alignment=”center”][vc_single_image image=”2111″ img_size=”full” add_caption=”yes” alignment=”center”][vc_single_image image=”2114″ img_size=”full” add_caption=”yes” alignment=”center”][vc_single_image image=”2113″ img_size=”full” add_caption=”yes” alignment=”center”][vc_single_image image=”2183″ img_size=”full” add_caption=”yes” alignment=”center”][vc_single_image image=”2184″ img_size=”full” add_caption=”yes” alignment=”center”][vc_single_image image=”2109″ img_size=”full” add_caption=”yes” alignment=”center”][vc_column_text]
September 1982 – Took time off college and drove down to Georgia with Doug Sievers and friend Susan, aka the “Topless Taxi”. We borrowed the boat from Elmer Painter and used SCUBA gear to access deeper parts of the river. See my Log Book story “Agatized Coral” for a full story about this river.
[/vc_column_text][vc_single_image image=”2185″ img_size=”full” add_caption=”yes” alignment=”center”][vc_single_image image=”2186″ img_size=”full” add_caption=”yes” alignment=”center”][/vc_column][/vc_row][vc_row css=”.vc_custom_1646976291797{padding-bottom: 40px !important;background-color: #6b6b6b !important;}”][vc_column][vc_column_text]
[/vc_column_text][/vc_column][/vc_row]