A new lichenometric dating curve for southeast Iceland
- Author:
- Bradwell T.
- Year:
- 2001
- Journal:
- Geografiska Annaler
- Pages:
- 83A(3): 91-101
- Url:
This paper presents a new lichenometric dating
curve for southeast Iceland. The temporal framework for the
curve is based on reliably dated surfaces covering the last 270
years, making it the best constrained study of this nature conducted
in Iceland. The growth of lichen species within Rhizocarpon
Section Rhizocarpon is non-linear over time, with larger (older)
thalli apparently growing more slowly. The linear 'growth'
curves derived previously by former authors working in Iceland
represent only part of a curve which has an overall exponential
form. Reasons for the non-linearity of the new dating curve are
probably physiological, although climatic change over the last
three centuries cannot be ruled out. Use of linear 'growth' curves
in Iceland is problematic over time-spans of more than c. 80 years.
Pre-20th century moraines dated using a constant, linear relationship
between lichen size and age are probably older than previously
believed. Those moraines lichenometrically 'dated' to the
second half of the 19th century in Iceland may actually pre-date
this time by several decades (30-100 years), thus throwing doubt
on the exact timing of maximum glaciation during the 'Little Ice
Age'.
- Id:
- 12388
- Submitter:
- zdenek
- Post_time:
- Monday, 16 March 2009 13:48