sim.strat {coffee}

Simulate the radiocarbon dating of random depths of a sediment which has accumulated over time.

Description

Simulate the radiocarbon dating (or with dates that are already on the cal BP scale) of a deposit that is known to have accumulated over time, and for which therefore the dated depths can be safely assumed to be in chronological order.

Usage

sim.strat(
  name = "mystrat",
  age.min = 4321,
  length = 800,
  n = 5,
  offset = 0,
  scatter = 2 * error,
  error = 0.02,
  min.error = 10,
  rounded = 0,
  strat.dir = "strats",
  sep = ",",
  cc = 1,
  postbomb = FALSE,
  ask = TRUE
)

Arguments

name

Name of the simulated stratigraphy. Defaults to "mystrat".

age.min

Minimum age of the simulation.

length

Length of the sequence.

n

The amount of dated depths.

offset

The ages could be offset by some constant value. Defaults to 0.

scatter

There is always a degree of scatter between measurements, and the amount of scatter can be modelled using, e.g., scatter=2*error. Set at 0 to model radiocarbon dates that are 100% faithful to the calibration curve (very unlikely!).

error

Laboratory error of the radiocarbon dates as percentage of the mean. Defaults to 0.02.

min.error

Minimum laboratory to be reported. Defaults to 10 (C-14 year).

rounded

Rounding of the simulated calendar years. Rounds to single years (0 decimals) by default.

strat.dir

The directory where the folders of the individual trees live. Defaults to tree.dir="trees".

sep

Separator for the fields in the .csv file. Defaults to a comma.

cc

Calibration curve to be used. Could be 1 (IntCal20; default), 2 (Marine20), 3 (SHCal20) or 4 (custom curve).

postbomb

Negative C-14 ages (younger than 0 cal BP or AD 1950) should be modelled using a postbomb curve. This could be 1 (northern-hemisphere region 1), 2 (NH region 2), 3 (NH region 3), 4 (southern hemisphere regions 1-2), or 5 (SH region 3).

ask

Ask if a folder may be made and files written into it

Details

Dates further down the sequence should have older ages than dates further up, even though owing to scatter, the dates themselves might not be in exact chronological order. The modelling is performed in a Bayesian framework (see strat). The amount of scatter, the laboratory error and an offset can also be modelled.

Value

A file containing 5 columns: the simulated calendar ages, the radiocarbon ages, their errors, their relative positions (starting with the youngest one at top, and counting upward going down the sequence), and the calibration curve to be used.

Author(s)

Maarten Blaauw, J. Andres Christen

Examples

  stratdir <- tempdir()
  sim.strat("ordered.mud", age.min=1000, length=5000, n=10, strat.dir=stratdir)