Long Term Plants Can Grow Directly on Sandstone Bedrock: Evidence from the Alexandria Pike Road Sandstone (Ridgeley Formation)

The JUNIATA JOURNAL of GEOLOGY, 1, 1-4 (2014)

Review Article Long Term Plants Can Grow Directly on Sandstone Bedrock: Evidence from the Alexandria Pike Road Sandstone (Ridgeley Formation)

Michaela Dempsie

Sandstone, as bedrock, has the capability to provide the essential nutrients a plant needs to thrive. The pore space in sandstone is a key factor that allows plants to obtain these essential nutrients within the rock itself. One of the reasons for this is because the moisture, trapped in the rock, is carrying many key nutrients a plant needs to survive. A plant needs both macronutrients and micronutrients. Even though sandstone is a very porous rock, moisture still gets trapped in the pores and the water gets moved around within the sandstone. The pores also create a space where plants can grow their roots. As

these roots are growing and breaking up the rock, the formation itself is leaving off CO2 which is both helping to cool the atmosphere around the formation and giving the plant the carbon dioxide it needs to grow. The bedrock in which a plant grows has a significant impact on why plants can survive.

Keywords.—Sandstone; Plants; Porosity; Micronutrients; Weathering

Department of Geology, Juniata College, 1700 Moore Street, Huntingdon PA 16652. Email: [email protected]

INTRODUCTION size, and the depositional environment in which the cementation process is taking place. The Ridgeley sandstone formation can provide (Worden & Morad, 2009, p.39) all the essential things a tree needs to grow. This formation is part of a bigger formation called the The main things plants need to grow on bedrock Oriskany formation, which was formed during are water, minerals, CO2, and a place to grow the Devonian time period. This sandstone roots. (Barta, 2009, p.37) The general nutrients a formation is formed primarily from sand sized plant needs are P, K, N, Mg, Ca. (Roccuzzo et quartz. Over a long time these particles of sand al., 2012) Trees will take up these nutrients as will cement together to form a sandstone. There ions. These ions were not originally ions, but are many different factors that affect the quartz became ions by being dissolved in water. The cementation process. Some of these factors are plant gets its water from the pores in the the temperature history of the quartz, the grain sandstone. This space in the rock formation PLANTS GROWING DIRECTLY ON BEDROCK

provides a way for the plant to grow roots, place and the parts that are remaining are the access water, and obtain nutrients. Another ones that have not been weathered away yet. reason trees can grow directly on bedrock is because they can keep the atmosphere in which INTERPRETATIONS they live cool by growing there roots in to the The rock formation along Alexandria Pike Road rock which gives off CO2 for the plant to use to is made up of quartz sandstone and is part of the grow and keep it cool. (University of Oxford, Oriskany formation whose age is early 2014) This CO2 comes from the breaking down Devonian. Sandstone is known to be very porous of the rock itself through mechanical and most people don’t think of it being able to weathering, because sandstone can hold CO2 hold or transport water through the rock which directly in the rock. in fact it can do. In South Africa there was a OBSERVATIONS study done on sandstone moisture regimes because on the particular sandstone in which the There are two parts to this formation, the main study was being done on contained ancient art focal point and the other parts surrounding that that is currently being weathered. The sandstone focal point. These parts surrounding the focal along Alexandria Pike Road is also being point have been weathered away and are still weathered away, but even though there is an part of the main focal point. This main focal environmental difference between to two point looks like a rock coming out of the side sandstones the one in Africa shows that moisture and top of the little hill. This formation is a little has been moved to the surface of the rock taller than two cars stacked on top of one causing the weathering and flaking of the another and consists of many different crevasses. paintings on the sandstone. (Mol & Viles, 2010) Besides the main focal point of this formation This shows that even in a hot environment that there are also smaller parts to it. These smaller moisture can be held in sandstone, so the parts surround the focal point and range in size sandstone along the road should be able to hold from regular car tires to truck tires. On one of moisture. This moisture is being held in the these smaller parts there is a tree growing pores of the sandstones. Water is held in these directly off the side of it. The tree is located in a spaces due to capillary action, which allows the gap in the rock. This geological feature is grey sand particles around the pore to hold on to the when far away and then as people go closer it water. When a pore gets to big then gravity will looks more like a brownish green color with exceed the strength of the capillary forces and moss growing on both the main focal point and the water will be pushed out of the pore. If the the other parts of the formation. When people pore space is small then the capillary action will blow directly on the rock little particles come be stronger then gravity and the water will start off. This shows that this particular sandstone has to move up to the pore space above the one it not been completely cemented. The grains of was originally in. this rock are the size of the pointy end of a push pin. This formation is made primarily out of Pore elasticity of a sandstone decreases with quartz particles. This formation has already gone higher pressures. This means that as the pressure through significant weathering because there is increases on the sandstone the pores get smaller soil around this whole formation and because the and as the pressure decreases the pores get smaller parts that look separate from the bigger. (Blocher, Reinsch, Hassanzadegan, formation really are not separate. They only look Milsch, & Zimmermann, 2013) There is not that separate because of the weathering that took much difference in one individual pore space,

DEMPSIE

seeing as though sandstone is a somewhat rigid quantities compared to the amount of structure, but when all the pores in sandstone get micronutrients a plant needs. added up this can make a huge difference in the amount of moisture particular sandstones can These different nutrients that a plant needs can hold. The sandstone in Africa has moisture in it be found in rain water or in running water over and it is also has more than one atmosphere of the surface of the earth. The Ridgeley sandstone pressure on it because it is located underneath formation along the Alexandria Pike Road can another type of rock. (Mol & Viles, 2010) So the easily obtain both sources of water because the sandstone along Alexandria Pike Road should formation does occur along a hill, which water have the capability to hold more moisture in the can run down and on the way down the hill it rock then the one in Africa because this one has can pick up these different nutrients. The rock less pressure on it because there is nothing can also get some of the nutrients through rain + above the rock except the atmosphere. This water. Rain water is acidic so it carries H ions decrease in pressure makes the pore space in the in it so that’s how it can react with both the soil sandstone bigger, but not by such a big amount it comes in contact with and the rock formation 2- - that the force of gravity beats the capillary itself, it also can contain SO4 and NO3 ions. ( forces acting in the pore space. Krupa, & Nosal, 1999) Depending on the soil or rock formation the water comes into contact Moss and trees are growing on this part of the with depends on what things are in the water. If Ridgeley formation. Moss and trees are able to the rain water runs over soil that is a pasture grow here because the rock formation is able to then the water is more likely to have a fair provide them with the things that they need to amount of nitrates in it. The Ridgeley formation grow. Moss can temporarily store nitrogen in the along the road isn’t downhill of a pasture so it rock, and obtains its nutrients through air borne won’t pick up nitrates in that way, but it is particles. (Krmar, Radnovic, & Hansman, 2014) surrounded by organic matter which will contain This nitrogen being stored in the rock is one of these different nutrients. This water that is the macronutrients nutrients that a tree needs in surrounding the rock will leak down into the soil order to grow, but the nitrogen stored in the rock and eventually into the rock below. In the case is not in a form that the tree can use. The of this formation the rock below is the formation nitrogen has to first get put in a form that the and through the rocks capillary action the water tree can use. This process can be done by will be brought back up through the rock. bacteria that live around a tree’s roots. All plants Another reason why plants can live directly on a have a certain amount of both macro and micro rock formation is because as the plant roots nutrients that they need in order to stay alive. grow into the formation they are breaking up the The micro nutrient a plant needs consists of Iron, rock. The process of weathering that is Manganese, Copper, Zinc, Molybdenum, Boron, happening allows the rock formation itself to and Chlorine. Plants use these nutrients in their release CO2 that it has. This breaking of the enzymes such as Laccase and Aconitase. Micro formation releases CO2 into the atmosphere, nutrients aren’t only needed for enzymes they which will cool down the atmosphere around the can also be used in giving a plant protection plant. (University of Oxford, 2014) This would against infections. (Sharma, 2009) explain why weathering rocks on hot summer Macronutrients that a plant needs are nitrogen, days are cool. potassium, and phosphorus. These are the nutrients that are needed in relatively high Plants have a certain requirements that a host must meet for the plant to survive. One

PLANTS GROWING DIRECTLY ON BEDROCK

requirement is that the host must have sufficient formations make great hosts because they space for roots to grow along with a source of contain or can provide all these requirements to water. Another requirement is that the host has the plant. This shows that the bedrock which a to be able to provide the plant with the right plant is growing directly on has a significant nutrients, especially seeing as though the plant impact on whether a plant can live on it. can’t get up and move by itself. Some rock

REFERENCES

Batra, V. (2009). Impact of Physical Environment on Plant Growth. Plant Ecology (pp. 37-81). New Delhi: Oxford Book Co..

Blocher, G., Reinsch, T., Hassanzadegan, A., Milsch, H., & Zimmermann, G. (2013). Direct and indirect laboratory measurements of poroelastic properties of two consolidated sandstones. International Journal of Rock Mechanics and Mining Sciences, N/A, N/A. Retrieved February 10, 2014, from the Science Direct database.

Krmar, M., Radnovic, D., & Hansman, J. (2014). Correlation of unsupported 210Pb activity in soil and moss. Journal of Environmental Radioactivity, 129, 23-26. Retrieved February 18, 2014, from the Science Direct database.

Krupa, S, and M Nosal. "Rainfall composition in Minnesota: integrating the chemistry, synoptic meteorology and numerical modelling." Environmental Pollution 104.3 (1999): 477-483. Science Direct. Web. 23 Feb. 2014.

Mol, L., & Viles, H. (2010). Geoelectric investigations into sandstone moisture regimes: Implications for rock weathering and the deterioration of San Rock Art in the Golden Gate Reserve, South Africa. Geomorphology, 118(3-4), 280-287. Retrieved February 10, 2014, from the Science Direct database.

Roccuzzo, G., Zanotelli, D., Allegra, M., Giuffrida, A., Torrisi, B., Leonardi, A., et al. (2012). Assessing nutrient uptake by field-grown orange trees. European Journal of Agronomy, 41, 73-80. Retrieved February 18, 2014, from the Science Direct database.

Sharma, C. P. (2006). Plant micronutrients. Enfield, NH: Science Publishers.

University of Oxford. (2014, February 5). Tree roots in the mountains 'acted like a thermostat' for millions of years. ScienceDaily. Retrieved February 10, 2014 from www.sciencedaily.com/releases/2014/02/140205210436.htm

Worden, R., & Morad, S. (2009). Quartz Cementation in Sandstones. Chichester: John Wiley & Sons.