April 18 - 24, 2021: Issue 490

Dorothea Mackellar Poetry Competition 2021 entries now open


''Our poets are encouraged to take inspiration from wherever they may find it, however if they are looking for some direction, competition participants are invited to use this year's optional theme to inspire their entries."

In 2021, the Dorothea Mackellar Memorial Society has chosen the theme “Rich and Rare.” As always, it is an optional theme, so please write about whatever topic sparks your poetic genius.

For a copy of the wonderful theme poster, please click here.


*PLEASE NOTE: If you're registering as an individual student, put your HOME address in your personal details and not your SCHOOL'S address! The address you list is where your participation certificate will be posted!*


(primary school and secondary school, anytime during the competition period)

Teacher/parent - registration completed online (invoice will be emailed within 2 weeks of registration)

Log in to your page.

Enter student details and submit poem(s) (cut and paste or type in poem content direct to the webpage) PLEASE DO NOT UPLOAD POEMS AS ATTACHMENTS AS THAT FUNCTION IS FOR POSTAL ENTRIES ONLY.

Repeat step 3 for every student/individual poem.



Have a read of the judges' reports from the previous year. They contain some very helpful advice for teachers and parents alike!

It is recommended for schools to appoint a coordinator for the competition.

Only a teacher/parent can complete the registration form on behalf of the student/child.

Log-in details: username is the email address and a password of your choice.

Log-in details can be given to other teachers/students for poem submission in class/at home.

Log-in as many times as necessary during the competition period.

Teachers can view progress by monitoring the number and content of entries.

Individual entries are accepted if the school is not participating or a child is home schooled. Parent needs to complete the registration form with their contact details. Please indicate 'individual entry' under school name and home postal address under school address.

Invoice for the entry fee will be sent to the registered email address within 2 weeks.

‘Participation certificate only’ option available for schools where pre-selection of entries has been carried out. Poems under this option will not be sent to judges, students will still receive participation certificate for their efforts.

Please read the Conditions of Entry before entering. Entries accepted: March 1 to June 30, results announced during early September.

Visit: https://www.dorothea.com.au/How-to-Enter-awards

Calling all budding artists ages 9 to 21

Enter the 5th Northern Beaches Youth Street Art Prize sponsored by Dee Why RSL and If u like ART. This year’s competition finalists will be displayed online with the chance for the public to vote for their favourites. 

Entries close 30th April and there is $2,000 in cash prizes to be won across different age groups.

 Winners will be judged by one of the Northern Beaches leading street artists and announced on 7th June. 

To enter just email an image of your artwork, full name, age, title, medium used and contact number to george.katos63@gmail.com 


 Mona Vale Mountain Cub Scouts

Find out more about all the fun you can have at Mona Vale Mountain Cub Scouts Profile

our Profile pages aren’t just about those who can tell you about Pittwater before you were born, they’re also about great clubs and activities that you too can get involved in!

The Wiggles: animals alphabet

Published 2021 by The Wiggles

Subscribe to our channel for more Wiggly videos: http://ab.co/WigglesYouTube

Seal Pup Birubi Makes Her Debut at Taronga Zoo Sydney!

Published by Taronga Zoo Sydney March 31, 2021

WilderQuest online fun

The NSW National Parks and Wildlife Service is pleased to present the WilderQuest program for teachers, students and children.

The WilderQuest program includes a website and apps with game and video content, Ranger led tours and activities in national parks across NSW. It provides opportunities for families to experience nature, science and Aboriginal culture in classrooms, online, at events and in national parks. The Teacher portal and free primary school resources have been produced with support from our Environmental Trust partners.


Mona Vale Library runs a Lego club on the first Sunday of each month from 2pm to 4pm. The club is open to children aged between seven and twelve years of age, with younger children welcome with parental supervision. If you are interested in attending a Lego at the Library session contact the library on 9970 1622 or book in person at the library, 1 Park Street, Mona Vale.

Children's Storytime at Mona Vale LibraryMona Vale Library offers storytime for pre-school children every week during school terms. Children and their carers come and participate in a fun sing-a-long with our story teller as well as listen to several stories in each session, followed by some craft.  

Storytime is held in the Pelican Room of the library in front of the service desk. Storytime is free and no bookings are required. 

Storytime Sessions: Tuesdays  10.00am - 11.00am - Wednesdays  10.00am - 11.00am  - Thursdays  10.00am - 11.00am

Profile: Avalon Soccer Club
Avalon Soccer Club is an amateur club situated at the northern end of Sydney’s Northern Beaches. As a club we pride ourselves on our friendly, family club environment. The club is comprised of over a thousand players aged from 5  who enjoy playing the beautiful game at a variety of levels and is entirely run by a group of dedicated volunteers. 
Profile: Pittwater Baseball Club

Their Mission: Share a community spirit through the joy of our children engaging in baseball.

National Geographic for Australian Kids

Find amazing facts about animals, science, history and geography, along with fun competitions, games and more. Visit National Geographic Kids today!

This week the National Geographic for Kids has launched a new free digital resource platform called NatGeo@Home to entertain and educate children affected by school closures.

The three main categories of content on the NatGeo@Home site aim to educate, inspire and entertain. For parents and teachers, there are also separate resources and lesson plans covering everything from getting to grips with Google Earth to learning to label the geological features of the ocean.

For the main Australian National Geographic for Kids, visit: www.natgeokids.com/au

For the National Geographic at Home site, visit:
Avalon Bilgola Amateur Swimming Club Profile

We swim at Bilgola rock pool on Saturday mornings (8:45am till 11:30am). Our season runs between October and March

Profile Bayview Yacht Racing Association (BYRA)

Website: www.byra.org.au

BYRA has a passion for sharing the great waters of Pittwater and a love of sailing with everyone aged 8 to 80 or over!
Profile: Ingleside Riders Group

Ingleside Riders Group Inc. (IRG) is a not for profit incorporated association and is run solely by volunteers. It was formed in 2003 and provides a facility known as “Ingleside Equestrian Park” which is approximately 9 acres of land between Wattle St and McLean St, Ingleside. 
IRG has a licence agreement with the Minister of Education to use this land. This facility is very valuable as it is the only designated area solely for equestrian use in the Pittwater District.  IRG promotes equal rights and the respect of one another and our list of rules that all members must sign reflect this.

For You This Week:

Front Page Issue 490 

North Narrabeen Welcomes Back Championship Tour At Rip Curl Narrabeen Classic Pres. By Corona

2021 Junior Lifesavers Of The Year Announced: Warriewood's Vivek Sirkari

Pictures NSW Seniors Festival 2021 Celebration By Local Senior Kevin Murray on a Walk along the Cowan Track: It's In Our Nature To Connect To Beaches, Bays, Birds, Bush, Beauty 

Aquatics Branch - State Surf Boat Carnivals Go Ahead Give A Good Splash For Local Crews At Season's End

Newport's Marlon Riley Wins 2021 NSW Bodyboard State Titles + locals win place in NSW Team 

Park Bench Philosopher Bayview Koala Sanctuary - a reprise of our 2012 history page

Seaweed Forests Festival, Manly: April 9th - May 9th, 2021 

Youth Week 2021Local Events Set To Inspire Creatives, Musicians, Good Sports and Lovers Of Recycled Fashion - April 16 - 24, 2021

Woodland Babies – Special scenes of six bird species in the Capertee Valley

Published April 12, 2021 by BIBY TV

These delightful woodland “babies” (aka fledglings or juveniles) of the species Jacky Winter (Microeca fascinans), Restless Flycatcher (Myiagra inquieta), Hooded Robin (Melanodryas cucullata), White-winged Chough (Corcorax melanorhamphos), Noisy Friarbird (Philemon corniculatus) and Speckled Warbler (Pyrrholaemus sagittatus) were filmed during three visits (late November 2020, early January 2021 and early February 2021) to the stunning Capertee Valley (NSW). This geological marvel is not only Australia’s largest enclosed valley or canyon (in fact, widest in the world), it is also recognised internationally as an Important Bird Area (IBA). Fragmented or remnant Box Gum Woodland (an EEC - Endangered Ecological Community) and adjoining wilderness areas provide refuge for several threatened or declining bird species. Moreover, decades of tree-planting (largely for the critically endangered Regent Honeyeater) has extended or recreated woodland vegetation on various (often covenanted) private properties. 

The filming site is one such property and one of the first in the planting program. As such, it is reaping the benefits of maturing planted trees (1995 – 2013), original woodland and open forest bordering Wollemi National Park, a magnificent old paddock tree (Yellow Box) looming over its offspring, remnant stands (e.g. on a small hill) and natural regrowth of trees, shrubs and native grasses in once denuded paddocks. The retention of standing and fallen dead timber also contributes to habitat quality. Many BIBY TV productions showcase the success of this revegetation (enter “Capertee Valley” into the search function on this channel). Again, this video is just a small window onto the way birds survive and thrive at this location. It’s particularly heartening to observe that the six species here (and many others) forage and nest in both existing and restored woodland (and often in transition zones, such as the lightly-timbered house area). The opening photo and scene at the 3.14 mark give a glimpse of relatively natural woodland, while the final photo reveals a regeneration area. 

Except for the Speckled Warbler section, the footage includes parent(s) and/or carers (in the case of the communal breeders, White-winged Choughs). The starring “babies” range from recently fledged (see early Jacky Winter scenes, White-winged Chough and Noisy Friarbird) to an older juvenile that closely resembles its parents (i.e. Speckled Warbler). Most of the families had two visible offspring; only the Speckled Warbler and Noisy Friarbird seemed to be without a sibling. Five out of six families were filmed across one to three days during a specific visit (i.e. late Nov for choughs, early Feb for warbler, and early Jan for robins, flycatchers and friarbirds). Only the Jacky Winter section includes “follow-up” footage (i.e. early Jan and early Feb). We are quite sure it’s the same family because of the short walking distance between the second filming location and the nesting/fledging area. We can though happily report sightings of older juveniles of other species in subsequent months. Given the “Vulnerable” status of Hooded Robins in NSW, it was especially cheering to see at least one of the youngsters in March 2021.

Credits: Bird footage and editing – Darren Broughton; Landscapes and text – Thalia Broughton

AUSSIES Wrap – Day 1 Youth Championships – 16 April

More than 700 young surf life savers from the U14 and U15 age groups gathered from across the country, with Maroochydore and Mooloolaba Beaches hosting the first day of competition.

In the U14’s it was Cooks Hills’ Alexander Walker who had the crowd on their feet, claiming the triple crown with gold in the U14 Ironman, Swim and Board.

“It’s incredible, it is so overwhelming it is such an amazing feeling to have completed the triple,” Walker said.

“The team at Cooks Hill and everyone is just so friendly, and we all work together at training to help each other improve as athletes and it is just a great atmosphere. It was great to come out here today and do it for them,” he said.

In the U15 Male Ironperson Newport's Conner Maggs has commenced his club's campaign with a bang securing silver and then following that up with gold in the U/15 Male Surf Race.

In the U14 Ironwoman final, a close run up the beach saw North Curl Curl’s Dominique Melbourn claim her first Australian gold medal after taking silver earlier in the day in the swim race.

“It’s such an unreal experience and I’m so lucky to have achieved the Australian title,” Dominique said.

“It’s surf and anything can happen, so I wasn’t confident until the end – but once I got down that last wave I got pretty excited.

“The club is really a team environment and we all work together so well, pushing each other through training. But nothing pushes us more than our coach Michael Clues.

“He’s such a determined coach and he just wants the best out of us and as it’s shown so far this weekend he’s definitely done that,” she said.

Former NSW Ironman legend and proud Wanda man Nathan Smith is helping usher through the next generation, with one of the Club’s stars Fletcher Warn taking out the U15 Ironman crown.

“Shout out to Nathan Smith and Greg Pierce for entering all the kids, none of this would have happened without you guys so thank you very much,” Warn said.

“To win it is just incredible. That was one of the scariest moments I have ever been in, I can’t, I pulled up onto the wave and I was like oh no cause I know he could run fast, so I had to get off and just run to get there.”

Jayda Kempton from Burleigh Heads Mowbray Park SLSC won the U15 Female Surf Race, a win that took her a bit by surprise.

“I’m a bit shocked actually – I went in to just have a go and I had no expectations to do as well as I did so I’m super happy,” Kempton said.

In the beach arena at Maroochydore the crowd was on it’s feet for the teams from Coogee, taking out both the U15 Female Beach Relay and the U15 Mixed Beach Relay Aussies titles and a Bronze medal in the U15 Male Beach Relay.

Eden Levitt from Coogee SLSC also took out a Bronze in the U15 Female Sprint and said she had no doubt in her mind that the two Beach Relay teams could get the Gold.

“Definitely two, I trust the relay team a lot, but it’s all experience it’s all new for all of us, there’s a lot to learn and A lot more to go,” Levitt said.

The local crew from Maroochydore took out the U15 Male Beach Relay ahead of Metropolitan Calounrda and Coogee with their coach saying the crew practiced changeovers multiple times to make sure they got it right.

“It’s exceptional for the young lads, they raced their hearts out and in such amazing competition awesome stringing a run together like that,” the Maroochydore coach said.

“The practiced over and over and over on the wrong side, upside down and forward and backwards and they’ve done it.”

The Australian Surf Life Saving Championships will be held on the Sunshine Coast from 16-24 April, with more than 5,900 competitors going head-to-head across three beaches and nine action packed days of competition.


For a full list of today’s results, click here.

Live stream

To watch today’s livestream, featuring the U14 and U15 Surf, Board and Ironperson Finals, click here.

Event Updates

For any updates and changes to schedules and timetables please download the Team App and join – Aussies 2021  to stay up to date with all the latest changes.

For further details about the Aussies and any other information head to – https://sls.com.au/aussies/

Ant Lion

About 3cm long, this is an adult Ant Lion, near Avalon Beach. In its earlier life in its pitfall trap it fed on ants and other small insects. Using its strong jaws it could grip the prey, suck out its vital juices and fling the carcass up out of the trap.

The pitfall trap: cleverly constructed with very fine sand at the angle of repose. As soon as an ant steps onto it, down it slides into the jaws of the antlion, invisible jaws open at the bottom of the pit.

Photos and text courtesy Pittwater Natural Heritage Association (PNHA)

Sculptural Trees: 100 Year Old Angophora Kept In Local Park

Here's an idea spotted during our Autumn School Holidays break while visiting Lane Cove/Greenwich. This tree is now Art as well as an adventure playground for local children. 


Nine new champions crowned at the 2021 Billabong Oz Grom Cup

April 11, 2021 at Park Beach, Coff Harbour

Nine new champions were crowned today at the 2021 Billabong Oz Grom Cup pres. by Coopers Surf Australia following a giant day of action in playful two-foot surf. 

Lennix Smith (Barrack Point, NSW) wrapped up his final year in the 2021 Billabong Oz Grom Cup pres. by Coopers Surf Australia with a bang, taking out the 16-and-Under Boys division. Smith surfed impeccably over the course of the event, consistently posting mammoth scores for mature manoeuvres and the final was no exception with the Illawarra natural-footer finishing the final with a solid 15.67 two-wave heat total.

Lennix Smith (Barrack Point, NSW) wrapped up his final year in the 2021 Billabong Oz Grom Cup pres. by Coopers Surf Australia with a bang taking out the 16-and-Under Boys division. photo by Ethan Smith / Surfing NSW 

Charlotte Mulley (Burleigh Waters, Qld) surfed like a seasoned veteran who had honed their backhand on the long righthanders of the Gold Coast as she claimed victory in the 16-and-Under Girls division. Mulley nailed a chain of massive backhand snaps to finish the heat with a 17.23 two-wave total and take the win ahead of Oceanna Rogers (Shellcove, NSW) who claimed the runner-up position. 

Sierra Kerr (USA) capped off a stellar Billabong Oz Grom Cup campaign, taking victory in the 14-and-Under Girls division. Despite a slow start in the final, Kerr was able to maintain composure in the dying moments of the heat and notch up a near-perfect 9.33 wave score for a chain of powerful snaps and carves – that appeared eerily similar to the same style as her Dad (former Championship Tour surfer Josh Kerr) – to jump from third position into the winner’s chair. 

Following on Sierra Kerr’s victory, Samuel Lowe (Port Kembla, NSW) became the second child of a former WSL Championship Tour star to take a win. Samuel appeared to channel his father Michael’s performance at the 2004 Quiksilver Pro at Snapper Rocks as he found a handful of beautifully tapered righthanders to post a massive 9.00 wave score and gain the upper-hand against some fancied opposition, including perennial standout Fletcher Kelleher (Freshwater, NSW). 

Following the recent Rip Curl Newcastle Cup that wrapped up yesterday, Ocean Lancaster (Newcastle, NSW) made sure he did his best to continue representing Novocastrian surfing abroad, smashing the 12-and-Under Boys division. Lancaster dominated the impressive final, executing a barrage of gigantic snaps and carves to finish the heat with a 17.07 two-wave heat total. 

Ocean Lancaster. photo by Ethan Smith / Surfing NSW 

Pipi Taylor (Peregian Beach, Qld) did the Sunshine Coast proud as she took out the 12-and-Under Girls division. Taylor posted a respectable 9.10 total to take the win ahead of her fancied opponents. 

Lucas Deffenti (Miami, Qld) showed he is a star on the rise as he took out the highly contended 10-and-Under Boys division. Deffenti stood out in the final, effortlessly linking a chain of giant snaps and carves to post a 15.23 two-wave total and earn the top spot on the dais. 

Leihani Kaloha Zoric (Byron Bay, NSW) claimed her second Billabong Oz Grom Cup title, taking out the 10-and-Under Girls division. Zoric surfed well beyond her years in the final exchange, nailing an array of beautiful snaps and carves to finish with a giant 16.34 two-wave heat total. 

Pheonix Talbot (Yamba, NSW) will be heading back to Yamba with his head held high after an impressive victory in the 8-and-Under Mixed division with a heat total of 10.60. The victory confirmed Talbot’s nous in Coffs beachbreak conditions, with the young up-and-comer taking out the same division in the Woolworths Surfer Groms Comp event back in late 2020. 

The prestigious five-day event – now in its eighth year – ran from the 7th – 11th April and catered for over 200 competitors in nine different divisions. 

Former champions include 2016 World Junior Champion and current WSL World Championship Tour surfer Macy Callaghan who claimed her respective division in the event’s inaugural year. Since then, the event has been won by a range of Australia’s best and most promising junior surfers. 

In addition to all the action in the ocean, the final days of the event were webcast through Surfing NSW’s social channels. 

All event presentations were hosted at the Hoey Moey. 

Boys and Girls divisions for the event included 8-and-Under Mixed, 10-and-Under, 12-and-Under, 14-and-Under and 16-and-Under.  

The Billabong Oz Grom Cup pres. by Coopers Surf Australia is proudly supported by Billabong, Coopers Surf Australia, Coffs Harbour Boardriders, Coffs Harbour City Council, Park Beach Plaza, Hoey Moey and Surfing NSW. 

Locana Cullen. photo by Ethan Smith / Surfing NSW 

Event results:

16-and-Under Boys

1 – Lennix Smith (Barrack Point, NSW)

2 – Eden Hasson (Port Stephens, NSW)

3 – Ty Richardson (Palm Beach, Qld)

4 – Kyan Falvey (Cabarita, NSW)


16-and-Under Girls

1 – Charlotte Mulley (Burleigh Waters, Qld)

2 – Oceanna Rogers (Shell Cove, NSW)

3 – Holly Wishart (Gerringong, NSW)

4 – Imojen Enfield (Port Macquarie, NSW)


14-and-Under Boys

1 – Samuel Lowe (Port Kembla, NSW)

2 – Fletcher Kelleher (Manly, NSW)

3 – Joshua Marsh (Barrack Point, NSW)

4 – Landen Smales (Peregian Beach, Qld)


14-and-Under Girls

1 – Sierra Kerr (USA)

2 – Shyla Short (Austinmer, NSW)

3 – Juniper Harper (Lennox Head, NSW)

4 – Ruby Trew (Manly, NSW)


12-and-Under Boys

1 – Ocean Lancaster (Newcastle, NSW)

2 – Hunter Anderson (Moffatt Beach, Qld)

3 – Ben Zanatta Creagh (Dee Why, NSW)

4 – Caden Francis (Palm Beach, Qld)


12-and-Under Girls

1 – Pipi Taylor (Peregian Beach, Qld)

2 – Avalon Vowels (Scotts Head, NSW)

3 – Charli Hatley (Currumbin, Qld)

4 – Lucy Darragh (Gerringong, NSW)


10-and-Under Boys

1 – Lucas Deffenti (Miami, Qld)

2 – Locana Cullen (Avalon, NSW)

3 – Luca Martin (Coffs Harbour, NSW)

4 – Jaggar Phillips (Maroubra, NSW)


10-and-Under Girls

1 – Leihani Kaloha Zoric (Byron Bay, NSW)

2 – Talia Tebb (Kincumber, NSW)

3 – Malia Watson (Tweed Heads, NSW)

4 – Henley Smith (Suffolk Park, NSW)


8-and-Under Mixed

1 – Pheonix Talbot (Yamba, NSW)

2 – Sage Lewis (Sandy Beach, NSW)

3 – Jaya Suhendra (Byron Bay, NSW)

4 – Bali Dobson (Byron Bay, NSW)

Curious Kids: why are some kids left-handed and others are right-handed?

Matthew Barton, Griffith University and Michael Todorovic, Griffith University

Why are some kids left-handed and others are right-handed? — Sofia, aged 8

Hi Sofia, thanks for your great question!

For a lot of human history, lefties have been seen as a little odd, and unfortunately some have even been treated very badly. For example, the word “sinister” comes from the Latin for “left” or “left hand”.

Luckily, some cultures have been more kind. The Inca, an old civilisation from South America, thought left-handed people had special spiritual powers. Also, it was good luck to be left-handed among the North American Zuni peoples. To be clear — there’s nothing wrong with being left-handed!

This preference for a particular hand is known as “handedness” and can be seen across many parts of the world.

Interestingly, only around one in ten people are left-handed. This means there are probably two or three kids in your class who will use their left hand to throw a ball or draw a picture.

It seems humans throughout history have preferred to use our right hand instead of our left. Evidence suggests our ancestors tended to use their right hand for tasks, perhaps like throwing rocks or picking berries, as far back as seven million years ago!

Why do we prefer one hand over another?

Sticking to one hand while writing a letter, drawing a picture, or throwing a ball helps make you better at performing those tasks.

Constantly swapping hands may mean the brain takes longer to learn how to do those things, so your brain tells you to favour a particular hand.

It’s also the reason why you probably prefer using a particular foot when kicking a ball. Remember, the more you kick with that foot, the better you become at kicking.

But it’s not just our hands and feet that we prefer one side over another when performing a task — even our brain does this!

An illustration of the human brain
The human brain has two big parts. One on the left, and one on the right! Certain abilities are linked with one side of the brain. Shutterstock

For example, your abilities to speak, do maths, and paint a picture prefer to sit on one side of the brain compared to the other.

Amazingly, the hand you use to write or throw a ball is often related to the side of the brain you use to speak. For example, if you use the left side of the brain to speak, you will likely be right-handed and the opposite is also true.

This relationship between brain function and handedness seems to be the reason why some people are left-handed, and some are right-handed.

When do we become left-handed or right-handed?

Which hand you use is not a choice. Rather, it’s a mixture of your genes which you get from your parents, and also your life experience.

Read more: Curious Kids: what are cells made out of?

Interestingly, identical twins, who share exactly the same genes, don’t always share the same handedness.

Most parents can begin to tell which hand their kid prefers by around two years of age.

However, scientists can accurately predict whether you will be left or right-handed before you are even born! By measuring which arm moves the most in babies still living in their mum’s womb, they can determine which hand you will prefer when you are born.

For now, even though lefties make up around 10% of the population, there are reasons to celebrate: August 13 is officially Left-handers Day! So, who’s got the upper hand now?

Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to curiouskids@theconversation.edu.auThe Conversation

Matthew Barton, Senior lecturer, School of Nursing and Midwifery, Griffith University and Michael Todorovic, Senior Lecturer, Griffith University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Curious Kids: how and when did Mount Everest become the tallest mountain? And will it remain so?

Brendan Duffy, The University of Melbourne and Sandra McLaren, The University of Melbourne

Most people know that Mount Everest is the tallest mountain but I want to know for how long it has been the tallest, and for how long in the future it will remain so (…) Which range preceded it? (…) When will something else overtake it? — Nigel, age 14, Christchurch

Nigel, thank you for this wonderful and insightful question. The answer is actually quite complex, since the height (or elevation) of mountain ranges in the past can be difficult to know.

However, it is a very important question as mountains have a huge role in the environment. They can disturb air flow, affect global and regional climate and provide opportunities for plants and animals to evolve.

Understanding the history of mountain ranges

Geoscientists address questions about ancient mountain heights by looking at sedimentary basins within mountain ranges. These are low areas where sediment materials such as pollen and plant leaves collect and minerals form in the soil.

A basin today may be much higher or lower than it was when sediment entered it. The fossilised pollen, leaves and minerals that date back to the time when the sediment was deposited can reveal how the landscape’s elevation changed over time.

If we look at fossilised pollen, we may find it comes from plants which likely grew in a particular range of elevation, and we may also notice the absence of certain other plants. (We can figure out where ancient plants likely grew by looking at their modern relatives.)

So by dating the pollen we find, we can calculate the landscape’s possible range of elevation in the past. We can conclude the landscape was too high for plant A, high enough for plant B (which gave us the pollen), but not high enough for plant C.

That is a pretty powerful capability, especially if the elevation of the landscape has changed significantly since the sediment was first deposited.

The Podocarp (southern hemisphere conifer) pollen on the left grew in Timor about 2.5 million years ago. A modern relative is shown on the right. These plants grew at elevations greater than 1.2km and are not present in older sediments. Their abrupt appearance in the sediment getting washed off the ancient island tells when parts of the island had grown to at least 1.2km high. Author provided

We can also look at the different kinds (or isotopes) of certain elements (particularly oxygen) contained in plant waxes, clays and carbonate minerals that form by chemical reactions in the soil. These plants and minerals incorporate rainwater.

As a band of rain reaches a mountain range, water with heavier oxygen isotopes falls out first. This means rainwater at higher elevations contains lighter oxygen isotopes, which then pass into the plants and minerals there.

If we find sediment that was deposited into a low basin 30 million years ago, but is now much higher, it will still contain oxygen isotopes that reveal the elevation at which it first formed. We can measure these isotopes to estimate how much higher the landscape has become.

How long has Everest been the tallest?

Everest is part of the Himalayas, a mountain range that stands at the southern edge of the vast Tibetan Plateau which is around 4-5km above sea level. Scientists have used the methods described above to understand the history of the plateau, which evolved as a result of several ancestral mountain ranges joining up.

Parts of the modern plateau were already higher than 3.5km by 26 million years ago. The southernmost of those ranges was a great, Andes-like mountain range called the Gangdese mountains.

These seem to have existed for more than 50 million years at elevations similar to those of the Andes today (about 4.5km).

However, south of the Gangdese, where we have today’s highest mountains, geologists found 34.5-million-year-old sediments from a shallow sea only a few dozen kilometres east of Mount Everest (locally called Qomolangma).

This tells us the part of the Himalayas that includes Everest, which now dominates the skyline, was not a mountain range back then. In fact, it was at sea level. It has grown more than 8km in the last 30 million years.

Everest, now the big kid on the block, is currently more than 100 metres higher than its closest rival. But a new victor will emerge with time.

What happens next?

To understand how Everest might lose its highest mountain status, we need to understand how mountain ranges are built. The largest mountain belts today were built from collisions between blocks of continental crust in Earth’s outer layer, the lithosphere.

As these blocks collide, they crumple and slices of rocky crust get stacked on one another, as seen in the right half of the cross section below. This gives birth to high mountains, which continuously rise and shift and change as the collision continues.

General cross section of lithosphere in the Himalayan Region
This is a general cross section of lithosphere in the Himalayan region. The lithosphere consists of all of the crust and part of the mantle, down as far as the partially-molten asthenosphere. x, Author provided

The video below helps visualise this process. It simulates the squeezing of a block of lithosphere in the Himalayas. You can refer to the “Sandbox Video” part of the cross section above to see where this process would occur.

University of Melbourne’s School of Geography, Earth and Atmospheric Science students squeeze layered sediments in a sandbox to see how they will deform.

You’ll notice the mountains begin to rise as soon as the collision begins. The arm pushing the sand represents the already thickened crust of the high Himalayas and the sand pile being pushed represents the Indian upper crust which lies below the mountain range.

The thickening moves to different spots over time. While the youngest and smallest mountain is furthest from the collision itself, the highest peak isn’t always in the oldest part of the range (where the collision began).

Eroding and growing

Large mountain ranges “erode” when changes in temperature, wind and water break down the rock and ultimately carry it away. Interestingly, erosion actually causes mountains to slowly grow over time.

This is a fascinating process geoscientists call “isostasy” which can be measured using GPS. The diagram below shows how the process is comparable to blocks of wood floating in water.

If intact blocks of a certain type of wood float in a pool, the same percentage of the overall volume will always protrude above the surface. So, if material is removed from one block, that block will rise.

This diagram shows how erosion of mountains — akin to cutting slots in blocks of wood — causes mountain peaks to increase in elevation. x, Author provided

We can compare these columns of wood to lithospheric blocks. As more erosion occurs, the mountain’s surface increases in elevation. This gives a way for deeply buried rocks to rise within the mountain range.

Hard to beat

Despite having 82,350km of convergent boundaries on Earth (where two plates meet and push together), it’s unlikely other mountain ranges will surpass the height of the Himalayas anytime soon.

This is because the Himalayas were built by the collision of two large continents composed of rocks with lower than average density. They therefore sit higher than the oceanic lithosphere.

One day in the distant future a new boundary will form somewhere and the forces creating the Himalayas will be removed.

The range will then collapse and eventually erode to become like the modern-day Appalachians in North America, which was an active mountain belt from between 325 and 260 million years ago.

Read more: Curious Kids: how do mountains form?

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Brendan Duffy, Fellow in Structural Geology and Tectonics, The University of Melbourne and Sandra McLaren, Associate professor, The University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.


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