Monday Geology Picture: Constantia Granite

Large granite rocks along a walking trail in Constantia, South Africa. January 2018.

For this week’s post, here’s a picture that I took yesterday during a Sunday afternoon hike with my family. We went for an easy stroll, baby and all, along the Alphen Trail in the Constantia region of Cape Town here in South Africa. My son is 3 months old now, and we’re just starting to go on some easy hikes as a family. The Alphen Trail is more of a walk than a hike, but nevertheless it was nice to spend some proper time outdoors again! In another month or two we hope to embark on some proper hiking.

There is too much vegetation along the Alphen Trail to see much geology, but along one part of the trail I did notice some interesting large granite boulders, which are shown in the above picture. These boulders no doubt belong to the ~550 million year old Cape Granite Suite. Large outcrops or boulders of these granites are commonly seen in the Cape Town area. For example, you can see large granite boulders at some of Cape Town’s beaches. However, I found these Constantia granite boulders interesting due to their weathering. While still quite large, there are clear signs that these boulders are being broken down through weathering. On the right, you can see a nice example of exfoliating granite weathering. On the left, you can see that a large boulder has split in two. In a few parts of the picture, you can see tree roots and other vegetation, which are no doubt contributing to biological weathering of the boulders.

Here’s a close-up view of the exfoliating slab:

Granite boulder, with my foot for scale.

Monday Geology Picture: Inselberg View

Some fantastic geologic scenery in Cape Town, South Africa: an inselberg (left) and the Twelve Apostles section of Table Mountain (right) in the background, a kayak in the middle, and some granitic rocks of the Cape Granite Suite in the foreground.

For this week’s picture, here’s a lovely view of an inselberg and the Twelve Apostles section of Table Mountain here in Cape Town, South Africa. Note the layers of sedimentary rocks of which the mountain is made. In the foreground, you can see some rocks of the Cape Granite Suite, which is about 550 million years old.

Monday Geology Picture: Granite Boulder in the Forest

For this week’s “Monday Geology Picture” here’s a shot of a pretty granite boulder that I spotted during a forest hike in the Constantia region of the Cape Town, South Africa. No doubt, this boulder consists of ~550 million year old Cape Granite. There’s no scale in this picture, but the boulder is about 2 meters wide.

Monday Geology Picture(s): Granite and Penguins at Boulders Beach, Simonstown

Last week I shared a few pictures from beautiful Boulders Beach just down the road in Simonstown, South Africa. This week I thought I’d share some more pictures of granite – and penguins! – at Boulders Beach. In the close-up shots, note gorgeous the potassium feldspar megacrysts in the granite. Most visitors to the beach focus on the penguins, but the granites are quite spectacular, too! Enjoy!

Boulders Beach #6. Note the megacrysts in this shot.

Boulders Beach #7. There are more megacrysts in this shot.

Boulders Beach #8. A close-up view of the granite, with shoe for scale. — Boulders Beach #8. A close-up view of some of the granite, with shoe for scale.

Monday Geology Picture(s): Boulders Beach, Simonstown, South Africa

Just down the road from where I live there is a fantastic place to observe gigantic granite boulders: Boulders Beach in Simonstown. Actually, you can see granite boulders on many beaches in the greater Cape Town area. These granites are part of the regional Cape Granite Suite and are roughly 550 million years old. However, Boulders Beach is special because it has a particularly good collection of large boulders… and it is also home to a penguin colony! Penguins and geology is a great combination for sightseeing!

Here’s a close-up of the picture above, showing the penguins:

And here’s another view of the spectacular granite boulders:

A field of granite boulders. — A field of granite boulders on the beach.

Monday Geology Picture(s): Oudekraal Beach, South Africa

A stunning location for a birthday. — A stunning location for a birthday party. In this picture my friend Kaylee and I check out some of the giant granitoid boulders by kayak.

Yesterday was my 30th birthday. Amongst other wonderful things, my husband Jackie organized a surprise birthday party for me at Oudekraal, a beautiful beach (and national park) here in Cape Town. Bordered on one side by gigantic boulders and turquoise-blue waters and flanked on the other side by tall, jagged, gray-green mountains, Oudekraal is a stunning location. Jackie rented a kayak, brought plenty of delicious picnic food, and invited many good friends for my party. The weather was beautiful, and we all had a great time. I’d never been to Oudekraal Beach before, but I hope to return soon!

Here are a few more views of gorgeous Oudekraal:

Anohter view of stunning Oudekraal. — Exploring the bay near Oudekraal Beach.

A jagged mountain range . — Jagged mountain peaks.

A seal came to visit! We saw several seals, actually.

Monday Geology Picture(s): Maine Geology Extravaganza!

Some neat fractured rocks (granite?) with veins (quartz?). Photo taken at Owl's Head State Park in Maine.

Adam and Kelly, my friends from college, recently (back in June) were married. For their honeymoon Adam and Kelly went to Maine. Adam was kind enough to send me some geology-themed pictures from their honeymoon, and I thought I’d share them here on Georneys. These pictures are from Owl’s Head State Park and Acadia National Park. I’ve provided a few notes about the photos, but please feel free to leave comments with additional insights and observations, particularly if you are familiar with the geology of the two parks. Perhaps we can tell Adam and Kelly a little more about the rocks they saw on their honeymoon. Here’s a great website by the National Park Service on the geology of Acadia National Park.

Here are some pictures from Thunder Hole in Acadia National Park:

Water rushing by granite in Thunder Hole.

At Thunder Hole water can splash up to 40 feet high! The hole is a popular tourist attraction, but you need to be careful when the sea is rough. In 2009 several people were swept into the ocean when they were visiting Thunder Hole.

Here are some pictures from Little Hunter’s Beach in Acadia National Park:

Interesting rock texture at Little Hunter's Beach.

Another view of the cobbles at Little Hunter's Beach.

Adam tells me that the cobbles from Little Hunter’s Beach were used in the past to pave New England streets. They certainly look like cobblestone street cobbles!

Thanks so much for sharing these pictures, Adam! Also, congratulations, Adam and Kelly!

Accretionary Wedge #42: Countertop Geology

OLYMPUS DIGITAL CAMERA — My friend's front entryway in Abu Dhabi. Can you spot the xenolith?

Ian Saginor of the blog Volcanoclast is hosting this month’s accretionary wedge, and this month’s theme is countertop geology!

Here’s the call for posts:

Have you seen a great countertop out there? Sure, everyone says it’s “granite”, but you know better. Take a picture, post it on your own blog or send it to me and I’ll post it for you. Do you think you know what it is or how it was formed? Feel free to include your own interpretation and I’m sure others will enjoy joining in the discussion. Ron Schott suggested that we expand the entries by including any decorative stone material that has been separated by humans from its source. This includes buildings, statues, etc. There’s a lot of really unusual stuff out there, so make sure to find a good one.

I think this is a great topic for an accretionary wedge! Anyone who has spent any amount of time with me knows that I am constantly looking at stone countertops, floors, walls, statues, and pretty much anything else made out of rock. Actually, I just visited by good friend Karima in Abu Dhabi, and she and her husband laughed at how I inspected the walls of all of the buildings we visited. I couldn’t help myself– there is some spectacular building stone to be found in Abu Dhabi. I was particularly impressed with all of the amazing building stones used in the Sheikh Zayed Mosque and the Emirates Place Hotel. My friend Karima actually joked that when we visited the Emirates Palace hotel and ate our gold-flaked dessert, I kept looking at the floors and walls rather than enjoying the spectacular ocean and city views. However, I’m actually planning to share pictures of those two buildings in other posts. For this accretionary wedge post, I’m actually going to share some pictures of my friend Karima’s front entryway to her house in Abu Dhabi.

Karima and her family live in a lovely two-story house (with a rooftop balcony) in Abu Dhabi. In front of their house, they have lovely slabs of granite decorating their front steps and entryway. They also happen to have a dark-colored xenolith just in front of their front door! The xenolith caught my eye as soon as I arrived at their house, and it actually reminded me very much of the dark-colored xenoliths I often observe in the Cape Granite here in Cape Town.

Here are some pictures of my friend’s front entryway xenolith:

And here’s a picture of a similar looking dark-colored xenolith in the Cape Granite here in South Africa:

: A similar looking dark-colored xenolith in the Cape Granite here in South Africa.

You may recognize the above picture as it was this week’s Monday Geology Picture.

Monday Geology Picture: A Dark-Colored Xenolith in the Cape Granite

: A little dark-colored xenolith (isn’t it adorable?) in Cape Granite, Clifton Beach, Cape Town, South Africa, October 2011.

I’m back home in Cape Town, so I thought I’d post a local picture for this week’s Monday Geology Picture. The above picture shows a small, dark-colored xenolith in the Cape Granite, a 550 million year old granite that has megacrysts (very big crystals) of feldspar. This xenolith is most likely a small piece of the Malmesbury Group, an older group of rocks that consists of alternating grackwacke sandstone and slate that have experienced significant uplift and metamorphism. The above xenolith was observed at Clifton Beach, a fancy beach area known for its bright white beaches which result from the weathering of the Cape Granite. Abundant xenoliths, such as the one above, can be observed in the granite boulders at Clifton Beach. I took the above picture when we took my husband’s cousin around to look at a few geological sites in the Cape Town area .There is a 5-Rand South African coin for scale in the picture; this coin is slightly smaller than an American quarter.

I have a few thesis deadlines looming, so for the next 2-3 months as I prepare for my thesis defense this blog may consist mostly of short picture posts. If time permits, I’ll try to slip in a few geology words and longer posts, but my thesis comes first at the moment. Hopefully the pictures will be enough to tide over my readers as I wrap up this PhD of mine.