[Matt Vogt]

First of all, I have to admit my ignorance as far as geology(among many other subjects) goes. Now that I have that out of the way, I wanted to confirm that fossil rock is a form of limestone, right?
Second, for this reason, I believe that it would be a bad thing for my future pond ph or alkalinity if I used fossil rock for my waterfall. Am I correct? I am hoping not, because I have as much as I can use available within a quarter mile from the house.

Thanks,
Matt

 

[jnic]

Matt,

Sorry, but limestone is NOT recommended for garden ponds (source).

john

 

[rpc7271]

Fossils are found in several types of rock, not just limestone.

 

[Matt Vogt]

Is there any way to tell if it is limestone? Maybe a pH test, or something?
I could (try to) post pictures if it would help anyone.

Thanks,
Matt

 

[KYYADA]

What is it a fossil of? Acid on limestone will make it fizz. If its shale it will break down....I think most limestone in your area would work out for you as long as you avoid the ones with shale streaks in them. By the way thanks for the piece of track, I ended up buying flex track and it bends so easily I canned the rail bender.

Johnny

 

[Pete Chimney]

Matt

I did my Master's thesis in Geology in SW Ohio where I went to Mami Univ. in Oxford. The Ordovician in SW Ohio/SE Indiana is some of the most fossiliferous section I have ever seen. My thesis, some 31 years ago, was on the paleoecology of Upper Ordovician bryozoans.

The rock you have could either be Ordovocian limestone or possibly the overlying Silurian, that is if you picked up the rock locally. Further north in western Ohio you will find even younger Devonian-aged limestones. The Ordovician and Silurian are usually good hard limestones that stand up relatively well to weather. There might be thin shale streaks within the limestones, especially in the Ordovician limestones, that with weather and time might cause it to break apart.

As for alkalinity problems I don't think you will have too much of a problem, your local water after all is in contact with these rocks on the surface and in the subsurface. The water you get from the tap will have been in contact with limestones and dolomites.

Test your water if you think you have a ph problem and adjust it accordingly with chemicals.

 

[Matt Vogt]

Wow! Thanks for all the info, Pete! I plan to build a smaller water feature out in the front of the house, so I will probably try the rock there first. The rock that I have is very solid with no shale, so I'm really not too worried about it breaking down, just hoping that it won't cause algae. What you said makes sense: the water is in contact with the rock, probably in my well, but I don't think algae would grow without oxygen, or at least light. Anyway, I am somewhat encouraged by your response. Hopefully I will be able to use the rock on both features.

Thanks,
Matt

 

[Biblegrove RR]

Wow, Pete! Very impressive... Can you tell me about my local limestone from the quarry? I just posted a question about this elsewhere before reading this. I want to use this rock in a riverway/waterfall pond in the front yard. My local landscaper told me not to because of algae growth. Until I find some fieldstone/creekrock locally, this is the cheapest alternative by far and comes in any size I want! It is very grey and has lines in it, I built a ring around fire pit and after getting very hot, they chip like crackers!
Should I hold out for a much more manual answer in creek rock?

thanks

 

[Torby]

Now there's a response from the expert!

 

[Greg Stevens]

Matt,

You're going to get algae no matter what you do or build with. The trick to keeping it under control is balancing the pond and/or using chemicals in it to keep the algae under control. There is a product on the market which my pond maintenance man uses in my pond and I have not had any problems with being over run with the green slime. It is a small block called Pond Block I think. It goes in once a month and I have had no problems since he started using it. Before that I had hair algae that was more than 2 ft long. Good luck with your ponds.

 

[Dougald]

The original question related to fossils in rocks ... and while fossilized remains of ancient organisms can occur in any rock, most were created by deposition of a substrate on top of the organism. This deposition is integral to the creation of sedimentary rock including limestone.

Here in the Ottawa Valley, there is an overlying layer of limestone (from the last 400 million years) on top of the very hard and ancient granites of the Canadian Shield. Outside of the Ottawa Valley, the Shield rocks predominate - most of these date back at least 1 billion years or more.

Stagnant water - whether on limestone or not - will eventually produce a bumper crop of algal growth. Just look at any swamp on the Canadian Shield for an example. This algae will start as green slime but will turn brown or other colours as the nutrients (and oxygen) in the water are depleted. In running water, hair like algae will grow but the slime on the surface will continuously be broken up - running water will generally stay very clean as the algae filters out nitrogen compounds from the waste of other organisms.

As has been mentioned, chemicals are available that will control the growth of algae. In a sterile environment, any brominating or chloronating agent will do ... more care must be taken if algae is to be controlled while allowing natural growth of organisms in your aquatic environment.

Regards ... Doug

 

[Webber]

Rock identification. Rock identification can be specialized but it can be simplified tremendously by some simple observations and tests you can do yourself. There are a few basic ranges of rocks.These broad types of rock mostly relate to how the rock was originally formed. First, what does the rock look like? Sedimentary rock comes in layers. If layers are obvious it might be sedimentary type. Conglomerate rocks are rocks that look like a big lump of granola, lots of identifiable bits suspended together. Does is look fairly uniform without layers? It may be igneous (heated molten rock that cooled down). Another way to classify your rocks is to determine their general hardness. Extremely soft rock can be scratched with your fingernail (like soapstone or talc). Some rocks can be scratched with a copper and zinc penny. If the rock is slightly harder but not as hard as diamonds, etc. you can scratch it it with a steel knife. Take a photo or two and post them. Once you've done these observations and tests, I'm confident our resident geologist can take it from there.

 

[Biblegrove RR]

Copper Phosphate used in ponds to kill agae would work I think? It takes the oxegyn out of the water and would probably harm any fish if placed in the pond though.
I can get picks in the morn, anf upload them. Can you tell me once more how to post them in here? Is it [ and ] before and after or what, I forget?
thanks!
I also have a few more questions I need help with after determining if I can use this limestone or not?

 

[Pete Chimney]

biblegrove

The rock around your home is a bit younger than the rock found near Cincinnatti. Your rock is approx. 320 ,000,000 years old or Mississippian in age. When you do heat limestone in a fire any thin shale streaks within the rock will tend to swell and as you found out the rock will split into thinner slabs or sheets. This is of course much the same process as leaving a rock out in the weather (minus the heating). Over time the action of water seeping into the shale and freezing and thawing will cause the rock to split apart.

Some limestones are more massively bedded and these make for good building stone. For example the rock south of Bloomington, Indiana is quarried for building stone and almost all of the courthouses and even the Empire State Building is faced with this limestone

Again the water you obtain from a tap/faucet or from a well is in contact with these limestones so there isn't any difference if you use these rocks in your pond, your water is still likely quite alkaline (i.e. pH>7).

 

[Matt Vogt]

Thank you, gents, for all of your responses. Lots of info to think about. I'll try to take and post pictures. I don't know why I hadn't thought of that.

It seems like there even if my well is in limestone it would be quite different than lining a pond, due to lack of oxygen and sunlight. Just a thought.


Thanks again,
Matt