|LANDFORMS OF THE NYC REGION PART III|
|For Printout # H-5, where do I find 'grain attachment' information?||Grain attachment information for each of the NYC materials may be found by looking at the pictures on the Geologic Materials Table. The materials underlying each landform can be determined by looking at your Bedrock and Surficial Geology Maps.|
|I am having a bit of a problem trying to figure out how to fill-in Printout # H-5, the "Deposition Evaluation Form". Am I supposed to refer back to Printout # H-4, "Depositional Features Checklist"? For example, suppose on Printout # H-4, for Agent = 'meltwater', I got 'gently sloping plain' as my landform shape. Does that mean that for NYC Landform = 'Gently Sloping Plain' on # H-5, I should put checkmarks for 'layering', 'sorting' and 'shape' that correspond to what I have for 'meltwater' on Printout # H-4?||Yes, to fill out Printout # H-5 successfully, your answers for 'layering' and 'sorting' should correspond to those you decided upon for Printout # H-4. As for 'shape', what you need to do is decide whether the NYC Landform in question (Gently Sloping Plain) has a counterpart amongst the three 'depositional shapes' ('B', 'GS', and 'H'). In this case it's obvious that there is a match: 'GS'. So, place a mark in the 'GS' column. |
For other NYC Landforms, 'B' or 'H' may match. Or there may be no match, in which case, no marks will be entered in any of the three 'shape' columns.
|It seems to me that for one of the NYC landforms, the answers for 'layering, 'sorting' and 'shape' completely support more than one of the depositional agents. Is that possible? And if it is possible, how can I tell which of the depositional agents is the right one?||Yes, it is possible. The observed characteristics of material and shape may indeed completely 'fit' more than one of the depositional agents. To tell which agent is probably the right one, observations of more characteristics would have to be made. Unfortunately, that is not possible in this exercise.|
|I am somewhat confused at the difference between 'structure' and 'landform'. Can you help me out?||'Structure' refers to the configuration of features such as layering within the materials of the earth. Layers, for example, can be horizontal, tilted, folded, or otherwise disrupted. All of these terms describe their 'structure'. |
'Landform' refers to the shape of the earth's surface in a particular place: whether it is a flat plain, a sloping plain, a valley, a hill, etc.
If a landform is composed of layered materials, there need be no correspondence between the configuration of the layers and the shape of the surface. For example, a hill may be composed of layers that are 'down-arched'; a valley may be underlain by layers that are 'up-arched'; and a horizontal plain may be underlain by layers that are 'tilted'. In other places, there may be a correspondence, so that hills are underlain by 'up-arched' layers; valleys by 'down-arched' layers; and horizontal plains by flat, horizontal layers.