{"id":2449,"date":"2013-04-22T21:17:43","date_gmt":"2013-04-23T02:17:43","guid":{"rendered":"http:\/\/oldnaturalist.com\/?p=2449"},"modified":"2024-05-18T13:41:10","modified_gmt":"2024-05-18T18:41:10","slug":"glacial-rocks","status":"publish","type":"post","link":"http:\/\/oldnaturalist.com\/?p=2449","title":{"rendered":"Minnesota Rocks"},"content":{"rendered":"

Minnesota has a rich geologic history<\/strong><\/h2>\n

Ancient Rocks 3.6 billion years ago. <\/strong>Morton Gneiss (pronounced “nice”) is one of the oldest rocks on Earth. Outcrops of gneiss can be found just an hour west of the Twin Cities in the town of Morton.
\n<\/strong><\/p>\n

\"sciencebuzz.org\"<\/a>

sciencebuzz.org<\/p><\/div>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

One Billion Years ago.<\/strong> Volcanoes on the North Shore of Lake Superior. Many of the rocks we are going to study are from that era, including:\u00a0 basalt and Lake Superior Agate.<\/p>\n

\"world-visits.blogspot.com\"<\/a>

world-visits.blogspot.com<\/p><\/div>\n

 <\/p>\n

Basalt lava flows north of Duluth from volcanoes one billion years ago.<\/p>\n

\"serc.carleton.edu\"<\/a>

serc.carleton.edu<\/p><\/div>\n

 <\/p>\n

450 million years ago,<\/strong> there was an inland sea that covered much of North America. The Twin Cities was underwater as evidenced by ocean fossils found in St. Paul. A few of the rocks we are going to study were formed during this time period including:\u00a0 Shale and limestone.<\/p>\n

\"fossilsandotherlivingthings.blogspot.com\"<\/a>

fossilsandotherlivingthings.blogspot.com<\/p><\/div>\n

 <\/p>\n

Prehistoric squid<\/p>\n

\"ocean.si.edu\"<\/a>

ocean.si.edu<\/p><\/div>\n

 <\/p>\n

Trilobite<\/p>\n

\"http:\/\/ledgardjespsonarchaeologyrebrand.blogspot.com\"<\/a>

http:\/\/ledgardjespsonarchaeologyrebrand.blogspot.com<\/p><\/div>\n

 <\/p>\n

 <\/p>\n

15,000 years ago\u00a0 <\/strong>Glacial Period\u00a0 – The glaciers moved only a few feet a year and carried\u00a0 many of the rocks we find today from Northern Minnesota to the Twin Cities area. Also when the glaciers melted it formed most of the lakes we see in Minnesota.<\/p>\n

\"cosmographicresearch.org\"<\/a>

cosmographicresearch.org<\/p><\/div>\n

Glacial ice<\/p>\n

\"commons.wikimedia.org\"<\/a>

commons.wikimedia.org<\/p><\/div>\n

Glacial Till.<\/strong> When the glaciers melted it left hills of rocks and sand that had been pulverized inside of the glacier. If you have a hill near your home, it was probably formed in this manner.<\/p>\n

 <\/p>\n

\"jesse.usra.edu\"<\/a>

jesse.usra.edu<\/p><\/div>\n

Glacial Lakes\u00a0 <\/strong>were formed when the glaciers melted. The weight of the ice caused the earth to be pushed down,\u00a0 forming what is called an ice block lake.\u00a0 (Lake Minnetonka in photo below)<\/p>\n

\"kruger.photoshelter.com\"<\/a>

kruger.photoshelter.com<\/p><\/div>\n

 <\/p>\n

Glacial erratics <\/strong>are large rocks that were carried on top of the glacier and did not get ground up\u00a0 inside of the glacier. When the glacier melted, the rocks dropped to the ground.
\nIf you have seen a large rock in your neighborhood, it is probably a glacial erratic.<\/p>\n

\"basementgeographer.com\"<\/a>

basementgeographer.com<\/p><\/div>\n

Glacial rocks are everywhere in your neighborhood environment. What is meant by “glacial rocks”? How did the rocks get in your neighborhood? What are the names and stories of some of the glacial rocks? Using the guide below, see what types of rocks you can find in your neighborhood.<\/p>\n

15,000 years ago a huge glacier covered most of Minnesota, Wisconsin and other states in the Northern US. As the glacier moved along it gouged out many types of rocks and carried them south moving at a speed of only a foot a day.<\/p>\n

Rocks that were inside of the glacier got ground up into smaller stones. If you have seen a large boulder in your neighborhood, it is called a “glacial erratic”<\/strong>. It was not inside the glacier, but rode on top of the glacier and was not ground up.<\/p>\n

When the Earth began to warm, the glaciers melted and the rocks inside came out, leaving what is called “glacial till”<\/strong>. Glacial till has many many sizes of rocks in it, from large boulders to sand. Many of the hills in our neighborhoods are made of glacial till. People mined the hills and sold the rocks for landscaping, road material, and concrete.<\/p>\n

\"www.mymagicelves.com\"<\/a>

www.mymagicelves.com<\/p><\/div>\n

 <\/p>\n

<\/p>\n

 <\/p>\n

Types of Glacial Rocks<\/strong><\/h2>\n

\"Sandstone\"<\/a><\/p>\n

Sandstone<\/strong>
\nSedimentary Rock
\nFormed from wind-blown sand
\nthat fell into shallow sea
\n400 million years ago<\/p>\n

 <\/p>\n

\"basalt\"<\/a>\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 Basalt<\/strong>
\nIgneous\/volcanic
\n1 billion years old
\nlava from North Shore
\nCarried by glacier<\/p>\n

 <\/p>\n

 <\/p>\n

Morton Gneiss<\/strong>\"Gneiss\"<\/a>
\nPronounced \u201cnice\u201d
\nMetamorphic rock
\n3.5 billion years old
\nOne of oldest rocks on Earth
\nUsed in buildings. Not a glacial rock.<\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

\"Shale\"<\/a><\/p>\n

 <\/p>\n

Shale<\/strong>
\nSedimentary Rock
\nFormed in shallow inland seas
\n1.9 Billion years ago
\nFound in Northern Minnesota
\nCarried in glacier<\/p>\n

 <\/p>\n

 <\/p>\n

\"granite\"<\/a><\/p>\n

Granite<\/strong>
\nIgneous Rocks
\n1.2 to 2.5 billion years old
\nFormed deep beneath the earth
\nCarried by glaciers from St. Cloud<\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

\"chert\"<\/a><\/p>\n

Chert<\/strong>
\nSedimentary Rock
\nFormed from shells of microscopic algae
\nUsed to make fire (flint)\/arrow points
\n2 billion years old<\/p>\n

 <\/p>\n

 <\/p>\n

\"Porphyry\"<\/a><\/p>\n

Porphyry<\/strong>
\nIgneous\/volcanic
\n1 billion years old
\nFound in lava flows
\nand roots of volcanoes
\nCarried by glacier<\/p>\n

\"MEJasper\"<\/a><\/p>\n

 <\/p>\n

 <\/p>\n

Mary Ellen Jasper<\/strong>
\nSedimentary Rock
\nFormed from fossilized algae
\n2 Billion years old
\nCarried by glacier from Iron Range<\/p>\n

 <\/p>\n

\"agate1\"<\/a><\/p>\n

 <\/p>\n

Lake Superior Agate<\/strong>
\nFormed from the weathering of igneous rock
\n1 billion years old\u00a0\u00a0\u00a0\u00a0 MN state rock
\nCarried by glacier from North Shore
\nof Lake Superior<\/p>\n

 <\/p>\n

\"Limestone\"<\/a><\/p>\n

 <\/p>\n

 <\/p>\n

Limestone<\/strong>
\nSedimentary Rock
\nFormed in shallow warm oceans
\n450 million years ago
\nCan have some fossils<\/p>\n

 <\/p>\n

 <\/p>\n

\"MilkyQuartz\"<\/a><\/p>\n

Milky Quartz<\/strong>
\nIgneous or Metamorphic Rocks
\n400 + million years ago
\nQuartz is used to make glass
\nQuartz is a common mineral<\/p>\n

 <\/p>\n

\"Ryolite\"<\/a><\/p>\n

 <\/p>\n

 <\/p>\n

Ryolite<\/strong>
\nIgneous\/volcanic
\n1 billion years old
\nLava from North Shore
\nCarried by glacier<\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

To download the Glacial Rocks Study Card 1: Click here<\/a><\/p>\n

To download the Glacial Rocks Study Card 2:<\/p>\n

GlacialRocks2<\/a> \"glacial<\/a><\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

Minnesota has a rich geologic history Ancient Rocks 3.6 billion years ago. Morton Gneiss (pronounced “nice”) is one of the oldest rocks on Earth. Outcrops of gneiss can be found just an hour west of the Twin Cities in the … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[12],"tags":[],"class_list":["post-2449","post","type-post","status-publish","format-standard","hentry","category-connecting-to-nature"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"http:\/\/oldnaturalist.com\/index.php?rest_route=\/wp\/v2\/posts\/2449","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/oldnaturalist.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/oldnaturalist.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/oldnaturalist.com\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/oldnaturalist.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2449"}],"version-history":[{"count":46,"href":"http:\/\/oldnaturalist.com\/index.php?rest_route=\/wp\/v2\/posts\/2449\/revisions"}],"predecessor-version":[{"id":12329,"href":"http:\/\/oldnaturalist.com\/index.php?rest_route=\/wp\/v2\/posts\/2449\/revisions\/12329"}],"wp:attachment":[{"href":"http:\/\/oldnaturalist.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2449"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/oldnaturalist.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2449"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/oldnaturalist.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2449"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}