Jonathan Cripps

Sessional Instructor

Program: PhD, Physical Geography

Supervisor: Tracy A. Brennand

Research: Reinterpreting the pattern and style of the last Cordilleran Ice Sheet deglaciation over the southern interior, British Columbia.

Reconstructions of former ice sheet deglaciation allow better anticipation of future ice sheet decay. The Cordilleran Ice Sheet (CIS), which existed over BC during the last glacial period to around 12,000 years ago, is currently considered to have deglaciated through vertical stagnation (top-down melting), though this has been challenged by recent studies. My research is a reinvestigation of the Nicola and Thompson river valleys in south-central BC, a key region in the development of the stagnation paradigm. I have reconstructed paleo-ice-dammed lakes from lake sediments and landforms throughout the valleys; these reconstructions have allowed paleo-ice margin positions to be identified, and these imply steady northwestward ice retreat to the Coast Mountains. Systematic and active retreat rather than stagnation is supported by the glacioisostatic tilts of the lake shorelines, which imply an ice surface slope up to the northwest, and several moraines and grounding lines within the region which suggest active ice retreat and minor readvances. These lines of evidence encourage a reinterpretation of CIS deglaciation in the southern interior as being systematic and active. Investigations of lake spillways (outflow channels) have revealed outburst flood sediment and landforms, improving understanding of post-glacial drainage network development in BC.  I am currently attempting to hydraulically model these floods.

Figure 1. Paleo-ice margins in the Nicola Valley reconstructed from moraines, paleo-glacial lake extent and meltwater channels, revealing systematic recession of a contiguous ice margin to the northwest. Blue arrows represent lake outflows and black arrows record glacioisostatic tilt directions and gradient (m/km) reconstructed from paleolake shorelines.
Figure 2. A sedimentary exposure in a moraine at Trapp Lake, southern BC. Folding and thrust faulting of silt, gravel and diamicton record a readvance over glacial lake and glaciofluvial sediment, and implies active ice retreat during deglaciation in southern BC.

Teaching:

Sessional appointments:
GEOG 412 – Glacial Processes and Environments
GEOG 213 – Introduction to Geomorphology

TA/TM appointments:
GEOG 102 – Global issues in a Geographical Perspective
GEOG 111 – Earth Systems
GEOG 213 – Introduction to Geomorphology
GEOG 311 – Hydrology
GEOG 312 – Natural Hazards
GEOG 313 – Fluvial Geomorphology
GEOG 412 – Glacial Processes and Environments

Publications:

Thorndycraft V.R., Cripps J.E., Eades G. 2015. Digital landscapes of deglaciation: Identifying Late Quaternary glacial lake outburst floods using LiDAR. Earth Surface Processes and Landforms. Published online June 30 2015. DOI: 10.1002/esp.3780

Previous education:

BSc Physical Geography, Durham University, UK.
Dissertation: Diurnal variation in discharge and suspended sediment concentration in an ice-marginal stream, Sandsfelljokull, Iceland. Supervised by Dr. Andreas Vieli.

MSc Quaternary Science, University of London (Royal Holloway and UCL), UK.
Dissertation: Quantifying the palaeohydrology of Glacial Lake Milfield and its outburst flood drainage: Implications for landscape evolution of the Till Valley (NE England). Supervised by Dr. Varyl Thorndycraft.

Scholarships and awards at SFU: