Virtual Field Trip from virtual-geology.info

Locality: Staithes, North Yorkshire

It is important that you access this field trip on a laptop or desktop PC. Click on any image to enlarge it.

SAFETY: if you visit this location, note that rock falls are frequent, and there has been a recent fatality. Do not approach the cliffs without first making a careful risk assessment, and wear a hard hat. This section is tide dependent - consult local tide tables, and only proceed eastwards beyond the harbour on a falling tide. Rocks on the foreshore are often slippery - wear suitable walking boots, and take care.

Where are we? At this location, we will study the Staithes Sandstone Formation of Pliensbachian age (Middle Lias - Lower Jurassic). Explore the area in Google Maps and Street View.

Geological map (we are at Locality 1 on the map)
Detailed stratigraphy

Click on the images to enlarge them.

A. View west to the Staithes Sandstone exposed in the cliff of Cowbar Nab, on the west side of Staithes Harbour. The base of the formation, in contact with the underlying Redcar Mudstone Formation, is not seen at this location.

B. The Staithes Sandstone section on the east side of Staithes Harbour. This is the section we shall study in detail.

Q1. There are two main lithologies seen in both these views. What do you think they are likely to be?

Q2. Describe the geometry of the sedimentary units, including their lateral continuity.

There is superb exposure, both in the foreshore at low tide, and in the cliff section. There's a lot to see and do at this location, and we usually spend about 3 hours here.

The aim of this exercise is to synthesize information of a variety of different types - for example lithology, thickness and geometry of sedimentary units, sedimentary structures and palaeocurrents, fossils and trace fossils (or absence thereof), lateral and vertical changes etc. From these observations, you should be able to attempt interpretations of the the processes and environments involved in the formation of the section. This integrated approach, using all available sources of information, is very important in sedimentology. We also need to consider the properties of each unit in terms of potential reservoir rocks, so we need additional information on, for example, connectivity and fractures.

Recording and interpreting the field evidence

The photographs below show the outcrops in more detail. Study and describe them, making notes, and use them as evidence on which to base your interpretations. You will use this information to construct a field log of one part of the outcrop. Pay particular attention to:

Field relationships - contacts between units, how units change as you trace them laterally, etc.
Sedimentary structures and how they change vertically and laterally.
Answer the questions attached to individual photos.

C. These bedding plane exposures occur at the horizon of the base of the section on the left of photo F.	D. Detail of the surface shown in Photo C. Q3. What are these structures, and what do they tell us about conditions of deposition?	E. The elongate fossils are scaphopods, a group of molluscs you may not have come across before. Find out more about scaphopods and how they lived. Other common fossils found here include Protocardia truncata, Oxytoma inequivalvis, and belemnites. Ammonites are uncommon. Left side of scale is in cm. Q4. What do the fossils tell us about the depositional environment?	F. A general view of the section to be logged, showing an alternation of rather clean fine sandstones (light colour) with intervals containing more siltstone (darker). Positions of Photos C, J, K, L are indicated - click to enlarge.
G. A closer view of the section shown in Photo F. Q5. How many lithofacies would you define in this section?	H. Another view of the section. Positions of Photos M, N.,O, P are indicated - click to enlarge.	I. Close-up of the base of the section immediately left of the gully in Photo H. Pole ~ 1m long.	J. Pay particular attention to the sedimentary structures in the sandstone bed with the pen (15cm long). Q6. Describe the basal contact of the sandstone.
K. Another view of the sandstone bed in Photo J. Coin 26mm diameter. Q7. Describe and identify the structures in the sandstone in Photos J & K.	L. Detail of the top of the laminated sandstone and the bed which overlies it in Photo K. Coin 18mm diameter. Q8. Identify the structures in the bed at the level of the coin. What do they tell us about conditions of deposition?	M. Top of a sandstone bed. Coin 18mm diameter. Q9. Describe and interpret the changes in sedimentary structures from base to top of the photo.	N. Partly overlaps with section in Photo I. Left side of scale is in cm.
O. A continuation to the right of the prominent sandstone bed in Photos N & P. Pen is 15cm long.	P. The prominent sandstone bed seen in the centre of Photo H.	Q. Detail of right side of photo P.	R. Detail of area to lower right of scale in Photo P.
S. Detail of area immediately below scale in Photo P.	Q10. Study Photos N to S. Describe all aspects of this sandstone bed, including its base, the sedimentary structures within it, and how they change upwards through the bed. What could this bed represent?

Constructing a log and interpreting the section

Construct a detailed graphic log through the section shown in photos F, G and H - base and top of the section are indicated in Photo F. Subdivide the log into numbered units. Indicate lateral changes within units. Ensure that your log shows lithologies, sedimentary structures and contacts, and that all symbols and colours used are explained in a key. Your log should fit on a single log sheet, with the key and overall interpretation on the back.
For each numbered unit or significant surface on the log, write a brief interpretation of the processes and conditions of formation in the right-hand column of the log. Include in your interpretation information such as environmental energy, flow regimes, salinity, oxygen levels, depth etc. There must be evidence to support all of your interpretations.
Suggest an overall depositional environment for the Staithes Sandstone.
In addition to the sedimentological properties of these rocks, what other visible features are likely to be important in determining the reservoir properties of each lithofacies?

Just for fun...

Captain James Cook (1728 - 1779) lived part of his early life in Staithes, and is commemorated at various points in the village and surrounding area. By coincidence, my Canadian relative, Victor Suthren, is a Captain Cook scholar.

This page is maintained by Roger Suthren. Last updated 16 November, 2020 8:02 PM . All images © Roger Suthren unless otherwise stated. Images may be re-used for non-commercial purposes.